Least I know which game I’m getting first when I get a Mega Drive again. I’m more curious than ever to see Virtua Racing on a crt playing on the actual system. Guess it will still vary on the kind of crt I hook it up to as well.
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This is why I made sure to qualify my statement and have in the past questioned whether or not the logic behind determining the correct phase for the systems used by the NTSC shaders was in fact correct.
I’m sure I can dig up my old posts with those questions.
So definitely no offense taken here. We’re actually on the same page.
Hi @PlainOldPants, as for Sega Master System, I’ve tried using your Patchy-Genesis.slangp inside ntsc folder, but for some reason, it didn’t look like I remember. I had a Master System in the 90’s. Surprisingly, using Patchy-snes.slangp I managed to get something very good and it remind me exactly the sms visual of that time. I had to change some params, though, because the default interference/noise was just too much for what I remember. It’s important to tell that at the time I was used to fine tunning my RF consoles to the best settings, so noise was minimized and my father had a 20" Panasonic CRT TV at the time, and it probably was too good in picture.
So, here’s my preset for master system the way I remember. Noise is noticeable only in some dark color shades. Fringing is subtle, so that it doesn’t distract you. No idea if I’m doing something stupid about the parameters, but here it is, anyway:
shaders = "16"
feedback_pass = "0"
shader0 = "shaders_slang/ntsc/shaders/patchy-ntsc/patchy-ntsc-encode-y-c.slang"
filter_linear0 = "false"
wrap_mode0 = "clamp_to_border"
frame_count_mod0 = "1000"
mipmap_input0 = "false"
alias0 = ""
float_framebuffer0 = "true"
srgb_framebuffer0 = "false"
scale_type_x0 = "source"
scale_x0 = "4.000000"
scale_type_y0 = "source"
scale_y0 = "1.000000"
shader1 = "shaders_slang/ntsc/shaders/patchy-ntsc/patchy-ntsc-combine-y-c.slang"
filter_linear1 = "false"
wrap_mode1 = "clamp_to_border"
frame_count_mod1 = "1000"
mipmap_input1 = "false"
alias1 = ""
float_framebuffer1 = "true"
srgb_framebuffer1 = "false"
scale_type_x1 = "source"
scale_x1 = "1.000000"
scale_type_y1 = "source"
scale_y1 = "1.000000"
shader2 = "shaders_slang/ntsc/shaders/patchy-ntsc/patchy-ntsc-noise.slang"
filter_linear2 = "false"
wrap_mode2 = "clamp_to_border"
frame_count_mod2 = "1000"
mipmap_input2 = "false"
alias2 = ""
float_framebuffer2 = "true"
srgb_framebuffer2 = "false"
scale_type_x2 = "source"
scale_x2 = "1.000000"
scale_type_y2 = "source"
scale_y2 = "1.000000"
shader3 = "shaders_slang/ntsc/shaders/patchy-ntsc/patchy-ntsc-separate-y-c.slang"
filter_linear3 = "false"
wrap_mode3 = "clamp_to_border"
frame_count_mod3 = "1000"
mipmap_input3 = "false"
alias3 = ""
float_framebuffer3 = "true"
srgb_framebuffer3 = "false"
scale_type_x3 = "source"
scale_x3 = "1.000000"
scale_type_y3 = "source"
scale_y3 = "1.000000"
shader4 = "shaders_slang/ntsc/shaders/patchy-ntsc/patchy-ntsc-decode-y-rmy-bmy.slang"
filter_linear4 = "false"
wrap_mode4 = "clamp_to_border"
frame_count_mod4 = "1000"
mipmap_input4 = "false"
alias4 = ""
float_framebuffer4 = "true"
srgb_framebuffer4 = "false"
scale_type_x4 = "source"
scale_x4 = "1.000000"
scale_type_y4 = "source"
scale_y4 = "1.000000"
shader5 = "shaders_slang/ntsc/shaders/patchy-ntsc/patchy-ntsc-eotf.slang"
filter_linear5 = "false"
wrap_mode5 = "clamp_to_border"
frame_count_mod5 = "1000"
mipmap_input5 = "false"
alias5 = ""
float_framebuffer5 = "true"
srgb_framebuffer5 = "false"
scale_type_x5 = "source"
scale_x5 = "1.000000"
scale_type_y5 = "source"
scale_y5 = "1.000000"
shader6 = "shaders_slang/ntsc/shaders/patchy-ntsc/trilinearLUT-switchable.slang"
filter_linear6 = "false"
wrap_mode6 = "clamp_to_border"
frame_count_mod6 = "1000"
mipmap_input6 = "false"
alias6 = ""
float_framebuffer6 = "true"
srgb_framebuffer6 = "false"
scale_type_x6 = "source"
scale_x6 = "1.000000"
scale_type_y6 = "source"
scale_y6 = "1.000000"
shader7 = "shaders_slang/ntsc/shaders/patchy-ntsc/linear-to-srgb.slang"
filter_linear7 = "false"
wrap_mode7 = "clamp_to_border"
frame_count_mod7 = "1000"
mipmap_input7 = "false"
alias7 = ""
float_framebuffer7 = "true"
srgb_framebuffer7 = "false"
scale_type_x7 = "source"
scale_x7 = "1.000000"
scale_type_y7 = "source"
scale_y7 = "1.000000"
shader8 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-first-pass-linearize-crt-gamma-bob-fields.slang"
filter_linear8 = "false"
wrap_mode8 = "clamp_to_border"
mipmap_input8 = "false"
alias8 = "ORIG_LINEARIZED"
float_framebuffer8 = "false"
srgb_framebuffer8 = "true"
scale_type_x8 = "source"
scale_x8 = "1.000000"
scale_type_y8 = "source"
scale_y8 = "1.000000"
shader9 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-scanlines-vertical-interlacing.slang"
filter_linear9 = "true"
wrap_mode9 = "clamp_to_border"
mipmap_input9 = "false"
alias9 = "VERTICAL_SCANLINES"
float_framebuffer9 = "false"
srgb_framebuffer9 = "true"
scale_type_x9 = "source"
scale_x9 = "1.000000"
scale_type_y9 = "viewport"
scale_y9 = "1.000000"
shader10 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-mask-resize-vertical.slang"
filter_linear10 = "true"
wrap_mode10 = "clamp_to_border"
mipmap_input10 = "false"
alias10 = ""
float_framebuffer10 = "false"
srgb_framebuffer10 = "false"
scale_type_x10 = "absolute"
scale_x10 = "64"
scale_type_y10 = "viewport"
scale_y10 = "0.062500"
shader11 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-mask-resize-horizontal.slang"
filter_linear11 = "false"
wrap_mode11 = "clamp_to_border"
mipmap_input11 = "false"
alias11 = "MASK_RESIZE"
float_framebuffer11 = "false"
srgb_framebuffer11 = "false"
scale_type_x11 = "viewport"
scale_x11 = "0.062500"
scale_type_y11 = "source"
scale_y11 = "1.000000"
shader12 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-scanlines-horizontal-apply-mask.slang"
filter_linear12 = "true"
wrap_mode12 = "clamp_to_border"
mipmap_input12 = "false"
alias12 = "MASKED_SCANLINES"
float_framebuffer12 = "false"
srgb_framebuffer12 = "true"
scale_type_x12 = "viewport"
scale_x12 = "1.000000"
scale_type_y12 = "viewport"
scale_y12 = "1.000000"
shader13 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-brightpass.slang"
filter_linear13 = "true"
wrap_mode13 = "clamp_to_border"
mipmap_input13 = "false"
alias13 = "BRIGHTPASS"
float_framebuffer13 = "false"
srgb_framebuffer13 = "true"
scale_type_x13 = "viewport"
scale_x13 = "1.000000"
scale_type_y13 = "viewport"
scale_y13 = "1.000000"
shader14 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-bloom-vertical.slang"
filter_linear14 = "true"
wrap_mode14 = "clamp_to_border"
mipmap_input14 = "false"
alias14 = ""
float_framebuffer14 = "false"
srgb_framebuffer14 = "true"
scale_type_x14 = "source"
scale_x14 = "1.000000"
scale_type_y14 = "source"
scale_y14 = "1.000000"
shader15 = "shaders_slang/crt/shaders/crt-royale/src-fast/crt-royale-bloom-horizontal-reconstitute.slang"
filter_linear15 = "true"
wrap_mode15 = "clamp_to_edge"
mipmap_input15 = "false"
alias15 = ""
float_framebuffer15 = "false"
srgb_framebuffer15 = "true"
scale_type_x15 = "source"
scale_x15 = "1.000000"
scale_type_y15 = "source"
scale_y15 = "1.000000"
pn_signal_res = "4.000000"
pn_width_uncropped = "256.000000"
pn_height_uncropped = "240.000000"
pn_rgb_blur_enable = "1.000000"
pn_scanline_dur = "47.700000"
pn_color_init_offset = "0.000000"
pn_color_line_offset = "0.333333"
pn_color_screen_offset = "0.333333"
pn_color_screen_offset_modulo = "2.000000"
pn_modulator_luma_filter_type = "-1.000000"
pn_modulator_chroma_filter_type = "0.000000"
pn_demodulator_std = "0.000000"
pn_gamma_type = "0.000000"
pn_connection_type = "-1.000000"
pn_noise_severity = "0.400000"
pn_noise_counter = "200.000000"
beam_min_sigma = "0.150000"
beam_max_sigma = "0.270000"
mask_type = "1.000000"
textures = "PhosphorSamplerLUT1;PhosphorSamplerLUT2;PhosphorSamplerLUT3;PhosphorSamplerLUT4;PhosphorSamplerLUT5;PhosphorSamplerLUT6;mask_grille_texture_small;mask_slot_texture_small;mask_shadow_texture_small"
PhosphorSamplerLUT1 = "shaders_slang/ntsc/shaders/patchy-ntsc/P22_80s_D65.png"
PhosphorSamplerLUT1_wrap_mode = "clamp_to_border"
PhosphorSamplerLUT1_mipmap = "false"
PhosphorSamplerLUT2 = "shaders_slang/ntsc/shaders/patchy-ntsc/P22_90s_D65.png"
PhosphorSamplerLUT2_wrap_mode = "clamp_to_border"
PhosphorSamplerLUT2_mipmap = "false"
PhosphorSamplerLUT3 = "shaders_slang/ntsc/shaders/patchy-ntsc/P22_J_D65.png"
PhosphorSamplerLUT3_wrap_mode = "clamp_to_border"
PhosphorSamplerLUT3_mipmap = "false"
PhosphorSamplerLUT4 = "shaders_slang/ntsc/shaders/patchy-ntsc/TrinitronP22_D65.png"
PhosphorSamplerLUT4_wrap_mode = "clamp_to_border"
PhosphorSamplerLUT4_mipmap = "false"
PhosphorSamplerLUT5 = "shaders_slang/ntsc/shaders/patchy-ntsc/P22_J_D93.png"
PhosphorSamplerLUT5_wrap_mode = "clamp_to_border"
PhosphorSamplerLUT5_mipmap = "false"
PhosphorSamplerLUT6 = "shaders_slang/ntsc/shaders/patchy-ntsc/TrinitronP22_D93.png"
PhosphorSamplerLUT6_wrap_mode = "clamp_to_border"
PhosphorSamplerLUT6_mipmap = "false"
mask_grille_texture_small = "shaders_slang/crt/shaders/crt-royale/TileableLinearApertureGrille15Wide8And5d5SpacingResizeTo64BGR.png"
mask_grille_texture_small_wrap_mode = "clamp_to_border"
mask_grille_texture_small_mipmap = "false"
mask_slot_texture_small = "shaders_slang/crt/shaders/crt-royale/TileableLinearSlotMaskTall15Wide9And4d5Horizontal9d14VerticalSpacingResizeTo64BGRshifted.png"
mask_slot_texture_small_wrap_mode = "clamp_to_border"
mask_slot_texture_small_mipmap = "false"
mask_shadow_texture_small = "shaders_slang/crt/shaders/crt-royale/TileableLinearShadowMaskEDPResizeTo64.png"
mask_shadow_texture_small_wrap_mode = "clamp_to_border"
mask_shadow_texture_small_mipmap = "false"
Screens: https://ibb.co/album/V3mb4p
3 Likes
There is no good NTSC Master System footage online at all. All the Master System gameplay videos on YouTube either are over RGB, over a Genesis’s composite, over an unspecified console’s (probably a Genesis’s) composite, or just recorded by a camera in shitty quality. I just need someone to upload a video capture of the SMS, preferrably an earlier one without the CXA1145. Prove to me that the NTSC SMS isn’t some 4chan hoax.
I can’t find a schematic for the NTSC Master System either, but there is a schematic for the PAL master system floating around. It has the same Sony CXA1145 setup as the early Genesis consoles, with the same inductor/capacitor filters on the signal, but I’ve read elsewhere that earlier NTSC Master Systems have a superior circuit using an older Sony chip.
That doesn’t necessarily mean that late NTSC Master System consoles had the same composite as the Genesis. Considering the Master System has a width of 256 pixels, there’s a good possibility it has the same phase pattern as the SNES, just with reduced artifacts and increased blur.
What that does mean @Hyllian is that you probably want to turn off the bilinear RGB blur (that’s really just a SNES thing), and change the modulator luma filter type to -2 (if that’s even in my latest upload), unless this looks too different from what you remember. For colors that look more like Grade, you can change my shader’s white point to 9300K, enable chromatic adaptation, and set the phosphors to either P22-J or Trinitron P22.
There are also 2 more tiny fixes I need to make in my code, particularly the Master System’s “blue lift” and the exact right SNES color carrier frequency–My 3-phase pattern currently is just slightly wrong. Once I do these 2 fixes, I’ll upload my latest version. This update is also going to calibrate the optional US red pushes better than before, and it’s going to add Grade’s 8500K white point.
1 Like
The No Swear Gamer records from hardware, you could ask him about specifics via Youtube.
Here’s another composite capture, from Japanese hardware: https://www.youtube.com/watch?v=9MHZDmmnkao
And here is another composite capture.The description says it’s “the original Master System”, there are also links where the same game (Shinobi) is demonstrated using the composite outputs of the Analogue NT Mini and the Genesis 1. https://www.youtube.com/watch?v=qLWZoEgjNnU
3 Likes
Thank you a lot. I saw a couple from The No Swear Gamer and didn’t know whether it was an original SMS or a Genesis, but those other 2 are probably original SMS consoles. They look like they’re the same as the Genesis’ video signal, except, comparing these two videos https://www.youtube.com/watch?v=creDKP43oCI https://www.youtube.com/watch?v=qLWZoEgjNnU the SMS and Genesis have different colors.
@Hyllian I’m questioning your memory a little bit. All of these videos have the Genesis “1-phase” pattern.
I did a quick search and found a PC-Engine video: https://www.youtube.com/watch?v=-sCRJ8ZhoUk It is a “2-phase” pattern.
For PS1, I’m not even going to look up videos. I’m just going to capture my real hardware.
I won’t start working on this stuff just yet. I have other things I need to dedicate more time to at the moment. All I’ll do for now is that tiny 3-phase fix and Grade’s SMS non-linear blue lift. After those things, one more thing in addition to trying to match these consoles is copying cgwg-famicom-geom’s adaptive comb filter.
(Edit: I’m already forgetting the color gamut conversions that I discussed with Chthon last month. The plan is to bake the entire color grading process into an LUT, including the demodulator settings, the gamma, and the phosphor gamut. It’ll be a big jump in quality, but… at that point, someone may as well get a CRT-compatible (!) colorimeter and just sample an entire LUT that way.)
2 Likes
Dunno if useful, but have you seen the composite filter/output comparisons over at the CRTdatabase with the Genesis related tables? For some reason, the original article where the Retrotink’s Notch filter is featured doesn’t seem to be there anymore, (here archived) but there are now explicit comb filter search values there, the filter pictures/tables are still available for Panasonic-ct-20sl15 and Panasonic-ct-20sl14j Edit: They info has now also been taken out from the Panasonic CRT articles.
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I can’t say my memory is correct. In fact, I doubt I can recover all these details from 30 years ago. 
You have a point.
BTW, dunno if it’s helpful, some schematics you can find here. There are some for sega systems and others for nes and atari clones made in Brazil.
1 Like
You sure the answer is not 42?
Hey there, hello boss. Sorry, haven’t made the time to check last version and Noise changes.
I found this new VHS record: Do you know if this VHS 1993 looking in Sonic 2 is actually achievable with current preset version? @sonkun @guest.r
As its stated in description, this is recorded from 1993 with Model 1 Genesis, RF cable, Rainbows and intense blurry looking. This is the perfect way to portray games from that decade. Would love to see it in action around here.
Audio is Mono and output rate seem like 16000 hz to me, in retroarch options.
Jump to 11:18 for rainbows and dithering
1 Like
Nice!
And this bug with Super sonic next to the signpost. I remember even this happening in a kids TV show where kids played through the phone buttons number. It really could break all game experience if this ever happened!
12:32
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Do remember that VHS can also have wow & flutter, tracking, dirty head and dropout artifacts due to physical tape or magnetic degradation.
You might need to add the VHS shader to simulate some of those “effects”.
2 Likes
Edit: I just realized that this update might have accidentally altered the Genesis artifacts, but I’m not sure. I might do another update soon to fix this, but I don’t have time at this exact moment.
This update has limited compatibility with presets made for the previous version. The shader passes are changed, so you will have to re-append all your presets. The only settings you need to update are “Tint”, “Color”, and “R-Y/B-Y lowpass type”.
This is a minor update doing several small fixes and improvments. The main things are slightly more accurate 3-phase, better red push default settings, the 8500K whitepoint, the SMS blue lift from Grade, and better performance. I recommend appending (in order) afterglow-update0 and crt-royale-fast. Consider prepending allowed-settings, to bring commonly used settings to the top of the list. https://www.mediafire.com/file/wgg42omjr7da398/patchy-8500k-2024-10-16.zip/file
I am going to put together a document going over this shader’s very long list of settings. Even though there are so many settings, only a few are really used. I’ve been short on time to work on this project lately, but I think this in particular can get done soon enough.
For those planning to make presets with this, I have a few suggestions. First, the settings to look similar-ish to Grade (but slightly more accurate) are Trinitron P22, 8500K, enable chromatic adaptation, r-y/g-y/b-y preset 0, and brightness 0.1. Second, if you use Grade’s BT.1886, you have to disable Auto Contrast and use the “color ramps” test pattern to set your contrast manually. Third, this update changed the default “R-Y/B-Y Lowpass Type” from 2 to 1 to reduce shadows and smearing, but you might consider changing it back to 2 for a more RF-like look. Fourth, for SMS, I recommend picking either one of the two patchy-genesis options, disabling “Genesis Jailbars on Solid Backgrounds”, and changing “Genesis Plus GX color fix” to SMS (2). A couple generic 2phase presets were added for consoles like PC-Engine and PlaySattion 1.
Detailed changelog and future goals
Full list of changes:
- Added a generic “2-phase” preset based on Maister NTSC / NTSC Adaptive. It is not based on any particular console, but it’s currently recommended for PlayStation 1. The “hi-res” version is meant for consoles with a horizontal resolution of about 420 or higher.
- Updated default Saturation (Color) and Hue Rotation (Tint) settings for US jungle chips. They look better now, but many people might think they’re all oversaturated.
- Sped up the noise generation, but it’s still a laggy piece of shit.
- Added more white point options, including 8500K for those who are used to Dogway’s Grading Shader.
- Can do chromatic adaptation with Trinitron P22 with white point 8500K. Make sure you use the specific 8500K option, not a custom CCT. Still, I prefer having chromatic adaptation off, because chromatic adaptation changes the appearance so much.
- Fixed the leaky integrator R-Y B-Y lowpass leaving behind a jailbar pattern in the signal.
- The leaky integrator on R-Y/B-Y is no longer the default. If you want the distinct chroma smear to the right, change the R-Y/B-Y lowpass filter type to 2, which is the leaky integrator.
- Changed default R-Y B-Y lowpass to a windowed sinc, and updated its default settings.
- Widened the decoder preset lowpasses to filter out the chroma signal more completely. Before, it was only just wide enough to make the chroma signal unnoticeable on many CRT shaders. Now, it’s much harder to notice even when using the signal shader alone.
- Halved the signal resolution for Genesis presets, giving better performance. The updates to the R-Y/B-Y lowpass were done because of this, because the Genesis would look wrong if you lowpassed in the old way.
- Added internal 3-phase and 2-phase settings taken from Maister NTSC / NTSC Adaptive. This fixes the SNES being slightly off. (I remember hearing somewhere that N64 has a similar 3-phase signal, but I don’t trust this.)
- Copied Grade’s Sega Master System blue lift. I haven’t properly put together an SMS preset, but for now, I recommend loading either the genesis-plus-gx or genesis-blastem preset (both work for this), turning off “Genesis Jailbars on Solid Backgrounds”, and changing the “Genesis Plus GX Color Fix” to 2 (SMS).
- Updated patchy-color a little bit to have the SMS blue lift and the updated saturation and tint settings. Patchy-color is a side thing that I’ve been paying little attention to, and that’s made very obvious by its messy code and missing features.
- Included bandstop and “anti-highpass” filters that both suck because they attenuate high frequencies so much. “Anti-highpass” especially is bad because it can cause some frequencies to get negated.
Goals for my next update are:
- Clean up the freaking code. Especially patchy-color. Compatibility with older presets might have to be broken severely.
- Better handling of varying horizontal resolutions.
- More accurate Genesis jailbars, by screenshotting a video capture, averaging all the lines, and using as a lookup table.
- More accurate match of Genesis color carrier settings. Currently, it’s just a little bit off.
- Make presets for PS1, SMS, and PC-Engine.
- Add an adaptive comb filter, probably heavily based on cgwg-famicom-geom’s.
- Add experimental PAL support.
- Add experimental support for LUTs that include the entire demodulate+eotf+phosphor+oetf process baked together, thanks to Chthon’s program called gamutthingy. Some fixes will have to be made to this later.
- Add R-Y/B-Y clamping levels, preferrably from same chips.
- Search up a bunch of demodulator chips on CRT-database and elsewhere, and pool together the results.
Other future goals:
- If not already done, update gamutthingy to allow RGB resultant values over 255, and automatically darken the entire LUT by a constant factor to make the whole gamut fit from 0 to 255.
- Bake the entire color grading process into an LUT, resulting in better performance and better colors. Improving my video signal is a higher priority for now.
- At that point, may as well get a CRT-compatible (!) colorimeter and make an LUT based on a real CRT, and/or try doing it by eye.
- More accurate EOTF, and other color accuracy improvements.
- Get more CRTs.
- Add support for hardcoded filters, like from Maister NTSC.
- See if it’s possible to create filters based directly on the inductor/capacitor circuits in the original Genesis. Up to this point, everything’s been done by eye.
- Better adaptive comb filtering.
- More accurate noise.
I just saw these posts about VHS. From some brief searching online, VHS compresses the video an awful lot. The tape itself contains a different kind of composite video signal which uses a much lower chroma subcarrier frequency, and a VCR has to convert standard composite video both to and from this VHS composite signal. This would mean, to update this shader to support VHS, I would make it modulate and demodulate the signal three times, using at least 4 additional shader passes.
3 Likes
I’ve spent these past 2 months focusing only on my university coursework. Even over the fall break, I was just spending most of the day working on course projects or studying. I just feel so relieved now, now that my most stressful, overwhelming university semester ever is finally over. No more of that servers-within-servers-within-servers nonsense.
Just this past week, I was able to get a cheap used colorimeter on eBay. My latest update here is a hasty attempt to use this colorimeter to approximate my 1989 RCA ColorTrak’s colors in a shader, with all of the imperfections that a consumer CRT has. The NES colors turned out nice, but the Genesis didn’t turn out quite right. This colorimeter likely has drifted over time.
This update has many other random changes too, which I made during what little free time I had.
This is also my last planned update to patchy-ntsc. I’m planning to ditch patchy-ntsc entirely and make another shader from scratch, which I hope will have much more bearable performance, cleaner code, better accuracy, and better familiarity and ease-of-use for other LibRetro shader users. This shader still can do much, much better with accuracy, since it currently is just doing rough guesses at the signal’s filtering/effects using windowed sinc functions, while it could benefit well from hardcoded LUTs or arrays instead, as seen in Maister NTSC and NTSC Adaptive. Plus, there are several improvements that just can’t be added into patchy-ntsc, such as Chthon’s full gamutthingy LUTs. By this update, patchy-ntsc has just gotten too patchy, with such high performance requirements and such messy, unmaintainable, unoptimized code.
In this release, I’ve decided not to include any CRT presets. Anytime I would append a “sanitized” CRT preset, the result would change too much. I recommend appending an interpolation shader, such as bicubic or b-spline.
Download at https://www.mediafire.com/file/idunzdx47lur8xb/colortrak_2024_12_16.zip/file and place all these folders directly inside your “shaders” folder, which contains another folder called “shaders_slang”.
I’ve also sampled an NES palette from this 1989 RCA ColorTrak, albeit with noise throwing off the results slightly. In comparison to the palette that I eyeballed from my 1995 Toshiba CE20D10 (which I no longer have), this is drastically different. Were all late-80s/early-90s CRTs like this? Since I couldn’t sample the D-column of the palette in the 240p test suite, I reused the grays from the 00 column, whereas in the shader preset pack above, I used simple bilinear interpolation to approximate guess the gray axis and de-emphasized colors. https://www.mediafire.com/file/98t1kvwl2x30s2c/colorimeter_palette.pal/file Note: This palette already is based on the final output colors. If you use it with a CRT shader, make sure you set both input gamma and output gamma to 2.2, and make sure any gamut-affecting settings just pass the color through. For instance, in crt-hyllian, set LUT to off.
Edit (2024-12-20): I have now done this same procedure on my 2000 Panasonic CT-36D30B. I will post the palettes and data in a bit. It allows you to set the white point to “warm”, “normal”, or “cool”, but funny enough, “warm” is actually the standard white (D65), whereas “normal” is 9300K, and “cool” is ~14000-15000K. All 3 had the same demodulation settings. Seeing as my 1989 RCA was about 9300K too, I think this is a pattern.
My methodology for reversing this CRT’s NTSC gamut correction
Spoiler (click to show/hide)
To try to replicate the colors for consoles other than NES, I measured three things. I am making several assumptions about how this CRT works which might throw off the result.
First, I sampled my CRT’s phosphors. I used the bottom row of the NES palette with high saturation and low brightness to isolate each individual phosphor. The results averaged to the following:
Red: x: 0.598576833333333, y: 0.35618925 Green: x: 0.303930178571429, y: 0.593650071428571 Blue: x: 0.153156090909091, y: 0.0663752121212122
(Edit: I’ve since used this same colorimeter to measure the phosphors and white points on my other CRT (which let me pick “warm”, “normal”, and “cool”), and the results were close to standard. The colorimeter is probably right. Regardless, I’m going to re-measure this 1989 CRT, just to be safe.)
Notice how this gamut mostly fits nicely into sRGB, with little need for gamut compression. This is great for my shader project, but I’m still doubting this colorimeter’s accuracy.
With this information, I’m able to represent any color from the CRT as a linear combination of these 3 phosphors, in linear space.
Second, I sampled a grayscale. I connected a cheap HDMI-to-composite converter to my laptop, and used HCFR to be able to easily sample the full grayscale from 0 to 255, but with only one sample per gray level, to save time.
Both the HCFR software and the HDMI-to-composite converter may have been altering the colors. I found that the input colors from 0-15 and 236-255 were getting clamped, which meant that something was interpreting my RGB as being in limited space from 16 to 235. With further trial-and-error, I found out that the grayscale approximated a gamma of about 2.1, which is about 2.4*2.2/2.5, meaning that something was correcting from sRGB gamma to NTSC gamma, while my CRT was outputting directly with approximately 2.4 gamma with no further corrections. The grayscale from the CRT did not have a steady white point (as expected from a consumer unit), so in Excel, I converted each xyY point into XYZ, and then into a linear combination of the 3 phosphors.
Once I had the full grayscale, I was able to take any color from the CRT, represent it as the 3 phosphors in linear-light space, and invert the CRT’s EOTF (a.k.a. gamma) to get the internal RGB values.
Graph of the grayscale: https://www.desmos.com/calculator/uoiwfketdn (Edit: This isn’t the right graph. If you want to see the grayscale, represented as linear Y luminance values for each phosphor, you can find it in my shader code, in patchy-ntsc-eotf.slang.)
Third, I sampled a full chroma cycle (500 colors) in YIQ space, keeping Y and sqrt(I^2 + Q^2) constant. I did this before realizing that the 16-235 clamp and the 2.2/2.5 gamma correction were happening, but when I graphed the data without correcting for those things, the result still formed very clean sine waves. The graph showed very clearly that this CRT is doing an ordinary R-Y/B-Y demodulation to correct the colors, as I saw in a number of chips’ documentation. I found that R-Y, G-Y, and B-Y were at these offsets and gains:
R-Y: offset 54.5168223778 degrees, gain 47.170890387 G-Y: offset 214.599290038 degrees, gain 15.5833234335 B-Y: offset 317.451910996 degrees, gain 52.5768429019 (I = 0 degrees, Q = 90 degrees, chroma radius: 0.1 (0 to 1) or 25.5 (0 to 255)) Gains are in RGB space. I had forgotten to take into account the 16-235 clamp and the 2.2/2.5 gamma correction, so the numbers are a bit off. Simply multiplying the gains by (235.0 - 16.0) / 255.0 makes the result more accurate.
Graph of R, G, and B in the full chroma cycle: https://www.desmos.com/calculator/kkazpj4z1a
The result had R-Y about 97 degrees off from B-Y, at about 0.9 relative amplitude, while G-Y was about 237 degrees off from B-Y at about 0.3 relative amplitude. This is similar to Sony’s JP axes in the CXA2025AS and CXA1644AS. This makes sense with the CRT’s white (mostly in the brighter half of the grayscale) being steadily near (x=0.28, y=0.295), which is close to 9300K, the reference white used in the Japanese NTSC standard at the time.
6 Likes
I really like the idea and am interested in a fast version. It does some unique things with the signal.
1 Like
Yay, Pants is back. Thank goodness.
1 Like
This zip file has 3 NES palettes based on my 2000 Panasonic CT-36D30B. The CRT allowed you to change the color temperature to cool, normal, or warm. Normal is about 9800K (0.2801, 0.2922), warm is about 7100K (0.3057, 0.3145), and cool is about 14400K (0.26066, 0.27436). The color temperature only changed the white balance without changing the demodulation settings. Like before with the RCA ColorTrak palette, these palettes are not finished because I did not sample the D-column, which I should’ve done using the 240p Test Suite’s IRE test. Instead, the D-column reuses values from the 0-column. https://www.mediafire.com/file/iaojvggifrutfsy/panasonic-ct-36d30b-colorimeter-palettes.zip/file
Unlike other NES palettes, these palettes already are gamma-fixed because they are sampled directly from my CRT using a colorimeter. If you use this in a CRT shader, make sure your “input gamma” and “output gamma” are both set to 2.4. If you only see one option, called “CRT gamma” (or something like that), set it to 2.2.
I’m pretty happy with the result. I think it’s a good improvement over the popular Sony CXA2025AS consumer palette and FCEUmm default palette, in that the 3-column is more like a bluish-purple instead of pink, the 2-column is more of a dark blue, the 6-column is a more pure red, and you get green 08, brown 18, and orange 28 at the same time. It is a pretty good American consumer palette, and drastically different from my 1989 RCA ColorTrak Remote E13169GM which is similar to the CXA2025AS’s JP axis setting.
For no reason, I’m also including two different attempts I made months ago to eyeball the palette from my 1995 Toshiba CE20D10, which I do not have anymore. For both, I put my laptop near the TV, and adjusted the color on my laptop until it looked similar to the CRT’s color from the 240p test suite. My first attempt was this https://www.mediafire.com/file/2ws9taf2uxp5j5b/manual_eyeballed.pal/file using some random color-picker website with a solid-color screen. The second here https://www.mediafire.com/file/xxa8ykx42o9ba0i/crtshader_manual_eyeballed.pal/file was similar, but it is less accurate, as I was doing it with a CRT shader (probably my “crt-advanced-personal-preset” from my previous downloads, but I don’t remember…) with the SNES 240p test suite to pick an RGB color with only 15-bit color (5 bits per color channel). I recommend the first one in favor of the second, but ugh, eyeballed color palettes are so ugly and bad, and the pinkish white point is so severely exaggerated. (If you average all 12 colors in the 3-row of the palette (31 through 3c) you get much closer to white C, but this eyeballed palette overexaggerates the pinkish white point.) I instead recommend using one of my 3 Panasonic palettes or my RCA ColorTrak palette. However, this Toshiba CE20D10 palette is special in that it has strong browns in the 8-column and cyans in the b-column at the same time. I know for sure this CRT has the TA8867AN, but in my time messing around with NES palette generation, I’ve never made the TA8867AN’s emulated output in my shaders look quite like this, probably because how how badly worn-out and overused the TV was.
Speaking of which, in a previous post here, I stated that my Toshiba CRT didn’t have “very orange yellows”, but I now remember that I had been changing the CRT’s “Tint” (chroma offset) setting to make yellow look normal. I’ve since learned that “Tint” should generally be centered on CRTs. Looking at my RCA and Panasonic TVs on the default Tint setting, the RCA’s default has a slightly orange yellow, a more pink magenta, and a normal cyan, while the Panasonic has slightly redder magenta and slightly oranger yellow; this is reflected in my latest and final patchy-ntsc release which sampled the R-Y/G-Y/B-Y offsets/gains using a colorimeter, as well as the directly-sampled NES palettes I’m posting which have similar results. Especially, the Toshiba CE20D10 palette messes up NES Battletoads badly, with brown ground in the first level, and a half-cyan title screen, both of which I remember happening with Tint set to its default–In other words, this TV was a total wreck that needed to be thrown away. I can assure that my RCA and Panasonic CRTs both are working well.
More in-depth info about this CRT (spoiler)
In terms of YIQ: (I = 0 degrees, Q = 90 degrees) (Not sure how precise) (Edit, later same day: Fix G-Y and B-Y gains being in the wrong units, while R-Y’s gain was in the correct units.)
R-Y: Offset 67.565130965, gain 1.799208485
G-Y: Offset 199.196534978, gain 0.813930348
B-Y: Offset 325.25680155, gain 2.067112454
Phosphors are basically the same as the standard. This makes it even more frustrating that I can’t get close enough to my RCA ColorTrak’s color in non-NES games.
Red: (0.641967333, 0.339582)
Green: (0.294701667, 0.607772333)
Blue: (0.148118, 0.066948)
The measures of the chroma cycle weren’t that precise. This time, to save hours of my time, and avoid burning in a rectangle in the middle of my irreplaceable back-breaking 36-inch comb-filtering beast CRT from 2000, I reduced the amount of chroma cycle samples from 500 to 100, and reduced the amount of gamma ramp samples from 256 to 64. (Edit: I don’t know why the “normal” and “warm” graphs on Desmos are the same, but I have 3 different results listed in my Excel spreadsheet. I averaged the three different results together to create the results above.)
Chroma cycle (Cool color temp) https://www.desmos.com/calculator/q6zg7owar8
Chroma cycle (Normal color temp) https://www.desmos.com/calculator/imifj3qgjx
Chroma cycle (Warm color temp) https://www.desmos.com/calculator/hi3ddiwqav
Normal gray ramps (LONG) (Used in conjunction with samples phosphors to invert gamma and get internal RGB values for the output of the full chroma cycle)
Cool
| 0.325825 | 0.325825 | 0.325825 | 0.325825 | 0.325825 | 0 | 0.081882 | 0.229763 | 0.221645 | 0.234217 | 0.227298 | 0.223461 | 0.235704 | 0.229452 | 0.235903 | 0.238511 | 0.240604 | 0.241047 | 0.2423 | 0.245222 | 0.23961 | 0.244896 | 0.246927 | 0.249793 | 0.251491 | 0.246709 | 0.248954 | 0.249537 | 0.254679 | 0.252887 | 0.25317 | 0.252904 | 0.253545 | 0.253574 | 0.255329 | 0.254776 | 0.253157 | 0.253145 | 0.255279 | 0.255362 | 0.255871 | 0.256331 | 0.255564 | 0.255527 | 0.255898 | 0.257933 | 0.256396 | 0.25762 | 0.257174 | 0.258261 | 0.258305 | 0.257574 | 0.258897 | 0.258473 | 0.258845 | 0.260232 | 0.258698 | 0.259715 | 0.259511 | 0.259897 | 0.260608 | 0.260585 | 0.26042 | 0.260026 | 0.261301 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.190482 | 0.190482 | 0.190482 | 0.190482 | 0.190482 | 0.969963 | 0.27783 | 0.312861 | 0.280423 | 0.279696 | 0.261919 | 0.235394 | 0.267399 | 0.247716 | 0.255055 | 0.262209 | 0.256126 | 0.263994 | 0.257417 | 0.266651 | 0.258777 | 0.258827 | 0.263639 | 0.2641 | 0.266198 | 0.25452 | 0.265934 | 0.263018 | 0.269643 | 0.264345 | 0.265418 | 0.266592 | 0.259001 | 0.265015 | 0.265461 | 0.266301 | 0.263559 | 0.262266 | 0.265808 | 0.263441 | 0.263717 | 0.263967 | 0.26249 | 0.266194 | 0.259432 | 0.266475 | 0.26231 | 0.264731 | 0.26564 | 0.263772 | 0.265868 | 0.263305 | 0.266122 | 0.263447 | 0.265424 | 0.266119 | 0.262891 | 0.267013 | 0.266323 | 0.265807 | 0.26651 | 0.265244 | 0.266416 | 0.262859 | 0.267433 |
| 0.00002 | 0.00002 | 0.00002 | 0.00002 | 0.00002 | 0.028461 | 0.061551 | 0.086605 | 0.160466 | 0.248908 | 0.329157 | 0.447624 | 0.57025 | 0.721451 | 1.055482 | 1.146492 | 1.42591 | 1.665656 | 2.031557 | 2.334238 | 2.719673 | 3.298308 | 3.497337 | 4.020119 | 4.520913 | 5.293955 | 5.688953 | 6.302712 | 7.094445 | 7.614383 | 8.415025 | 9.215246 | 9.924679 | 11.02029 | 11.521341 | 12.722216 | 13.326401 | 14.630997 | 15.728536 | 16.935003 | 17.836644 | 18.738285 | 20.244038 | 20.837134 | 22.256056 | 23.743497 | 25.356354 | 26.653438 | 27.351815 | 29.262272 | 30.357917 | 31.568033 | 33.062839 | 34.374588 | 37.273515 | 37.973855 | 39.989452 | 40.774798 | 42.781275 | 44.287096 | 46.589278 | 49.000389 | 50.496951 | 52.119068 | 53.69895 |
Normal
| 0.325825 | 0.325825 | 0.325825 | 0.325825 | 0.325825 | 0 | 0.237449 | 0.266842 | 0.249194 | 0.263395 | 0.256573 | 0.256272 | 0.263552 | 0.254744 | 0.26217 | 0.261294 | 0.267315 | 0.26934 | 0.264652 | 0.273525 | 0.267439 | 0.270474 | 0.271141 | 0.272417 | 0.273493 | 0.269337 | 0.272206 | 0.27195 | 0.275555 | 0.274916 | 0.273316 | 0.275299 | 0.273327 | 0.273451 | 0.273776 | 0.276525 | 0.275844 | 0.275682 | 0.277081 | 0.275158 | 0.27795 | 0.276868 | 0.276141 | 0.277278 | 0.277165 | 0.278859 | 0.276648 | 0.27796 | 0.279171 | 0.278154 | 0.279397 | 0.277981 | 0.278764 | 0.278596 | 0.280035 | 0.280202 | 0.279986 | 0.280218 | 0.27982 | 0.281296 | 0.280806 | 0.281611 | 0.281911 | 0.280442 | 0.28206 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.190482 | 0.190482 | 0.190482 | 0.190482 | 0.190482 | 0.9702 | 0.300414 | 0.40432 | 0.338369 | 0.335739 | 0.303616 | 0.261528 | 0.308371 | 0.281398 | 0.292344 | 0.291381 | 0.291388 | 0.298599 | 0.283621 | 0.29526 | 0.285553 | 0.287747 | 0.288512 | 0.293046 | 0.293306 | 0.277763 | 0.289743 | 0.283985 | 0.29155 | 0.287592 | 0.29476 | 0.288924 | 0.28384 | 0.288201 | 0.288578 | 0.290349 | 0.289441 | 0.285599 | 0.288372 | 0.28626 | 0.28779 | 0.286269 | 0.283016 | 0.288923 | 0.282616 | 0.288075 | 0.283489 | 0.287624 | 0.286989 | 0.28546 | 0.28839 | 0.284046 | 0.287778 | 0.285021 | 0.286824 | 0.287676 | 0.285246 | 0.287959 | 0.287142 | 0.287738 | 0.288882 | 0.287163 | 0.289079 | 0.285168 | 0.288698 |
| 0.00002 | 0.00002 | 0.00002 | 0.00002 | 0.00002 | 0.033097 | 0.070694 | 0.099424 | 0.195365 | 0.310009 | 0.401479 | 0.532335 | 0.730391 | 0.922627 | 1.316765 | 1.470746 | 1.85303 | 2.188852 | 2.60564 | 2.941631 | 3.536439 | 4.234412 | 4.59018 | 5.08705 | 5.987848 | 6.793072 | 7.346676 | 8.104446 | 9.09971 | 9.903031 | 10.995809 | 11.902337 | 13.007866 | 14.202925 | 15.102742 | 16.40172 | 17.502907 | 19.309907 | 20.206075 | 21.90955 | 23.10879 | 24.211801 | 26.220171 | 27.907158 | 29.224517 | 30.811766 | 32.023706 | 34.113503 | 36.31784 | 38.122946 | 39.414559 | 40.829763 | 43.017474 | 45.029562 | 47.725433 | 49.022518 | 51.034606 | 52.922963 | 55.727694 | 57.32792 | 59.22175 | 61.333715 | 63.824428 | 66.946825 | 67.728591 |
Warm
| 0.325825 | 0.325825 | 0.325825 | 0.325825 | 0.325825 | 0 | 0.386128 | 0.381331 | 0.292094 | 0.306808 | 0.292077 | 0.284663 | 0.294489 | 0.287449 | 0.29225 | 0.289607 | 0.293336 | 0.295105 | 0.294686 | 0.294473 | 0.289033 | 0.29428 | 0.298379 | 0.296851 | 0.297243 | 0.293497 | 0.297904 | 0.295752 | 0.298328 | 0.297508 | 0.299958 | 0.2973 | 0.296851 | 0.297636 | 0.299682 | 0.301235 | 0.298619 | 0.299325 | 0.301036 | 0.29867 | 0.300101 | 0.300232 | 0.300396 | 0.300994 | 0.300012 | 0.301028 | 0.300221 | 0.30147 | 0.302 | 0.301872 | 0.302649 | 0.301741 | 0.302514 | 0.301734 | 0.303075 | 0.304572 | 0.303634 | 0.304198 | 0.303831 | 0.304116 | 0.304635 | 0.305234 | 0.305269 | 0.304625 | 0.304381 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.190482 | 0.190482 | 0.190482 | 0.190482 | 0.190482 | 0.970339 | 0.604104 | 0.608785 | 0.38817 | 0.375995 | 0.340689 | 0.307695 | 0.345169 | 0.319376 | 0.315381 | 0.322457 | 0.315255 | 0.32224 | 0.309767 | 0.321806 | 0.311338 | 0.311757 | 0.313908 | 0.315814 | 0.312163 | 0.300145 | 0.312092 | 0.309428 | 0.314339 | 0.310756 | 0.309298 | 0.311172 | 0.305319 | 0.309919 | 0.307832 | 0.309561 | 0.307783 | 0.305015 | 0.308401 | 0.306463 | 0.30637 | 0.307352 | 0.303342 | 0.308633 | 0.301685 | 0.30908 | 0.303509 | 0.306314 | 0.305137 | 0.306141 | 0.307501 | 0.304658 | 0.307557 | 0.305498 | 0.306945 | 0.307115 | 0.304717 | 0.307874 | 0.307331 | 0.307327 | 0.308887 | 0.307287 | 0.307333 | 0.304259 | 0.30842 |
| 0.00002 | 0.00002 | 0.00002 | 0.00002 | 0.00002 | 0.036602 | 0.081706 | 0.116377 | 0.23158 | 0.367953 | 0.485461 | 0.672007 | 0.889401 | 1.132756 | 1.592094 | 1.793669 | 2.225557 | 2.667808 | 3.111657 | 3.651902 | 4.252405 | 5.230903 | 5.591024 | 6.266031 | 7.065965 | 8.197938 | 9.089879 | 9.990409 | 11.185688 | 11.987802 | 13.189048 | 14.784376 | 15.790659 | 17.283641 | 18.386792 | 19.683946 | 21.184225 | 23.48837 | 24.682068 | 26.683072 | 28.18349 | 29.580383 | 32.089616 | 33.774779 | 35.493125 | 37.170921 | 39.286534 | 40.677954 | 43.281453 | 46.575963 | 48.070839 | 49.580379 | 51.768159 | 53.674967 | 56.369083 | 57.670024 | 61.178813 | 63.662229 | 65.663302 | 67.562813 | 70.153404 | 71.663082 | 73.961685 | 78.17818 | 79.249832 |
Bright gray ramps (Also long) (Not used in any calculations, but included for anyone who might be interested in the future.)
Cool
| 0.325825 | 0.325776 | 0.21854 | 0.225325 | 0.233478 | 0.240617 | 0.243058 | 0.245211 | 0.247157 | 0.250357 | 0.250822 | 0.253362 | 0.255187 | 0.254915 | 0.256504 | 0.25722 | 0.257872 | 0.258601 | 0.259632 | 0.25957 | 0.259712 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.190482 | 0.661491 | 0.311974 | 0.269829 | 0.282816 | 0.265523 | 0.264612 | 0.275526 | 0.266276 | 0.273367 | 0.270239 | 0.267364 | 0.26738 | 0.268143 | 0.269596 | 0.272955 | 0.272203 | 0.270751 | 0.271078 | 0.27149 | 0.274506 |
| 0.00002 | 0.065846 | 0.3876 | 0.986082 | 2.256764 | 4.127276 | 6.809505 | 10.305288 | 13.520255 | 18.516432 | 23.628679 | 29.446807 | 34.657107 | 41.665008 | 48.671223 | 56.364731 | 64.780609 | 73.303661 | 82.316422 | 85.817636 | 85.692081 |
Normal
| 0.325825 | 0 | 0.253146 | 0.246778 | 0.258352 | 0.263751 | 0.265273 | 0.264553 | 0.269607 | 0.272774 | 0.272211 | 0.273558 | 0.275752 | 0.27596 | 0.277116 | 0.277724 | 0.279064 | 0.280578 | 0.281811 | 0.281096 | 0.280263 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.190482 | 0.97051 | 0.408558 | 0.316488 | 0.316751 | 0.291819 | 0.292892 | 0.300617 | 0.288775 | 0.296165 | 0.291035 | 0.288969 | 0.288237 | 0.289838 | 0.290638 | 0.294322 | 0.293868 | 0.293753 | 0.291894 | 0.291698 | 0.293547 |
| 0.00002 | 0.042087 | 0.293775 | 0.909132 | 2.270735 | 4.587804 | 7.796426 | 11.986387 | 16.000595 | 22.18849 | 28.797506 | 36.105039 | 43.011724 | 50.90681 | 58.805684 | 67.685663 | 77.389781 | 85.693428 | 94.811886 | 98.812001 | 99.693228 |
Warm
| 0 | 0.343174 | 0.266729 | 0.274919 | 0.281311 | 0.286553 | 0.292306 | 0.288531 | 0.29262 | 0.295474 | 0.294865 | 0.298295 | 0.299827 | 0.300056 | 0.301497 | 0.302073 | 0.303782 | 0.304069 | 0.305725 | 0.305676 | 0.304232 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.969215 | 0.645059 | 0.407052 | 0.342043 | 0.341739 | 0.317663 | 0.313541 | 0.322155 | 0.313504 | 0.317361 | 0.314504 | 0.311058 | 0.310414 | 0.311958 | 0.312317 | 0.315533 | 0.315273 | 0.313948 | 0.312167 | 0.31248 | 0.314471 |
| 0.019708 | 0.091201 | 0.581073 | 1.501156 | 3.477856 | 6.571391 | 10.585341 | 16.165316 | 21.370655 | 28.854018 | 37.148405 | 45.853246 | 53.95012 | 62.434932 | 71.226603 | 81.296839 | 90.591197 | 99.591605 | 109.40156 | 114.493948 | 114.770856 |
4 Likes
This isn’t a serious post or anything, but I was thinking about how some CRTs make the image bigger whenever the screen gets brighter, and how some CRTs also have these “shadows” to the right of bright objects. I ended up causing individual scanlines to stretch by different amounts.
Horizontal foldover, bright red/blue bleeding, shadows to the right of bright objects, scan velocity increasing the brighter the color is… So freaking ugly. I hate it.
I’ve create a monstrosity. Why do I always stay awake for hours past midnight coding these stupid things?
Anyway, here’s a download link if anyone wants to try it for some reason. Extract the shader files into any folder and load it in RetroArch. I don’t know why I named it “translate”, but whatever. https://www.mediafire.com/file/ak9arkl30y86gru/translate.zip/file
Oh my god
I just remembered, I made a gradual burn in shader last year too, but it stops being funny once the screen becomes too dark to see anything.
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I’ve managed to get a CRT that was manufactured 1985. (To be clear, this is in the USA.) It has some problems, but it works well enough to make a shader and an NES palette based on it. This year is important because of SMPTE-C becoming a thing in 1987, and early games on NES, Atari, etc. were played on TVs like this. (Though still, games made in Japan were meant to be seen on Japanese TVs, which follow a very different version of the NTSC standard.)
Unfortunately, the CRT has a couple problems. First, the CRT is broken in such a way where the brightness (black level) can’t be raised high enough. This prevented me from directly capturing an NES palette, so I had to use a program to generate it instead. Second, this CRT uses physical knobs for its settings instead of an on-screen display, so there’s no “reset” button to get the default Tint and Color settings. Even so, the brightness problem didn’t stop me from getting the phosphors, grayscale, and (relative) chroma demodulation settings, using my colorimeter. With this data, it’s possible to approximate the TV’s colors (with my chosen Tint and Color settings) in a shader in RetroArch.
You can download the shader and NES palette here: https://www.mediafire.com/file/9jpcd1n682hbdr4/toshiba_1985.zip/file (UPDATE: More hardware-accurate grayscale and gamma https://www.mediafire.com/file/z8fv3q9xcbko1rr/blackstripe_with_grayscale.zip/file) This time, I used ChthonVII’s program called gamutthingy to generate the NES palette and LUT. Their program uses advanced gamut mapping methods for better color accuracy.
When playing Genesis/MegaDrive games, use BlastEm for best results with this shader.
As I’m still learning how to use gamutthingy, this shader isn’t complete yet. In particular, I haven’t set up my sampled grayscale yet. Consumer CRTs are terrible at keeping the same white balance across their whole grayscale, and this one is no exception. BT.1886 doesn’t perfectly match any of my CRTs either. For now, the LUT shader and NES palette both have a constant white balance, and they use ITU-R BT.1886 for their EOTF. That’s as hardware-accurate as I’ll do tonight, but soon, I’ll set it up to use my CRT’s grayscale. I’ve added a new link above with these features added.
I’m planning to take one last try at sampling my 1989 RCA ColorTrak Remote, because my previous two attempts at it are clearly wrong. I’m not 100% sure, but I think I know how to do it right this time.
Of course, rebuilding my NTSC composite effect from the ground up is still a goal. The main goals are optimization, accessibility, and familiarity for other RetroArch users. I also have one idea that might or might not make the Genesis artifacts more accurate, but don’t count on it.
CRT info (Updated)
Phosphors. Each one is a geometric mean of 10 samples to remove RF noise. Compared to other phosphors seen in gamutthingy, this doesn’t seem quite right, but I’ll take what I can get.
- Red: 0.638994661420802, 0.34054912704359
- Green: 0.302680061977106, 0.611123488970143
- Blue: 0.143735472664549, 0.0703919024997988
Grayscale (used for EOTF) (excluding values that are too dark to be seen, due to the CRT’s brightness being too low)
- Y:
- Original data and first regression attempt: https://www.desmos.com/calculator/grt7wzpp4v
- Disgusting piecewise regression made by hand, as an Excel formula:
.
=IF(A16<20,0.00945707342805*(A16^2.36-0)+0.00002,
IF(A16<40,(0.00945707342805*(A16^2.36-0)+0.00002)*(40-A16)/20+(0.0376774871875*(A16^2-400)+10.739517)*(A16-20)/20,
IF(A16<60,(0.0376774871875*(A16^2-400)+10.739517)*(60-A16)/20+(0.155689133485*(A16^1.68-491.429004672)+57.097684)*(A16-40)/20,
IF(A16<80,(0.155689133485*(A16^1.68-491.429004672)+57.097684)*(80-A16)/20+(0.611867814498*(A16^1.4-308.611247805)+131.307476)*(A16-60)/20,
0.611867814498*(A16^1.4-308.611247805)+131.307476))))
(Created by hand using this annoying piecewise regression machine that I hate: https://www.desmos.com/calculator/bjltmbkzcr Why did I create such a horrible tool?)
- xy:
- White point averager tool: https://www.desmos.com/calculator/mt7vhz5wk7
- Regression: https://www.desmos.com/calculator/s6vnthtqnk
Note: Uncalibrated CRTs do not keep a consistent white point throughout their grayscale. The xy graph is showing how the white point changes as Y’ (from the YIQ/YUV video signal) changes.
Linear regression to get the demodulator settings: https://www.desmos.com/calculator/52qrtlqybr Clearly, this isn’t perfect, as the peaks of the sinusoids are a little noisy. https://www.desmos.com/calculator/5vxku72991 Updated to reduce noise (by using previous two regressions) and remove outliers for better precision
I can share my excel spreadsheets if requested, but the above information should be all that anyone needs.
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