I am working on a new version of these shaders right now and done a lot of test with real hardware and adjust parts of the shaders. For NDS however. It’s 99% accurate for the color accuracy, however the colors may have their gamma for each red, green, and blue signals very slight difference like some modern phones. Few shades of colors show a minimal differences of color, but it is very close to the hardware and it shouldn’t matter that much. It could be because the gamma isn’t as completely straight or something. One other reason is it could be the LCD dots being bright. I don’t have an equipment of color calibration tools since they are very expensive but I simply use the Red, Green, and Blue image to the NDS Phat to show the color gamut. I used Photoshop for hours to match the colors from the system and also match my monitor brightness to the level of the system, even though whites on NDS doesn’t have perfect whites, especially on the bottom screen. It’s very close on the top screen so I was able to get accurate colors while staying on better white level. All colors look very perfect, with minor exceptions said from above. Nevertheless, it does look the best playing Super Mario 64 DS and compare both shader and real system that looks indistinguishable. Although, I had to put the gamma a little high because the shadow parts shows more on the hardware.
As for the GBA, I did flash the same white light to the screen and compare it again. The current shader looks slightly cold on parts of the image that shows less olive greens and yellows being more peach tone. I did work on the shader again and shows a bit more olive green and yellow just like the real system. I do use light intensity to 2.5 which is the basis of what I capture from the system with bright light, which is around 1.8 gamma. It looks very close to the current shader except a slight more noticeable with olives and yellows, mostly warm colors that should show on the hardware.
I did plan to make a video for a long time and I do plan to start on it. The new shaders should come out by a few days and see how it turns out.
Edit 11/22: I uploaded the new version. I did some tweaking on the NDS to get the colors more accurate as the progress went on, and it should be fine. The GBA shader should show a bit more yellow than peach.
I did add slang shaders in the package with existing .cgp and equivalent. I did create three separate GBA glsl shaders to have brightness adjusted since glsl doesn’thave menu settings at all. Preferences on light intensity are varied, so that’s the reason.
New pictures of those shaders will come up tomorrow and a video should come up in December.
Also, a user posted pics of GBA models that shows different vibrance like the shaders here, and has a video in the blog: http://atomix.vg/2014/08/01/cual-es-la-mejor-pantalla-para-jugar-game-boy-advance/
I found this from retrorgb website.
Edit 12/9: I am working on a new method of the GBA shader. I found out that all the color values of each, red, green, and blue change when display gamma or “light intensity” change and it would darken a bit, which made me wonder why parts of the image on certain games looks a bit dark on the shader, but pops put in the real screen, and it wouldn’t matter for the phosphurs on the screen. Like Pokemon games for example, some of the colors of the overworld sprites are supposed to pop in a bit more than how the current shader process. I would leave the display gamma settings work, and change the target gamma or “darken strength” from VBA shader, to change the gamma of the raw image before the actual color effect change. I’ll explain how the gba screen works.
The GBA screen, for each red, green, and blue color phosphurs and white, usually have their light kept a bit when light source gets a bit dark, but when it gets dark enough, the luminance goes down so all three colors goes dark as well as the white, unlike the shader implement with “light intensity” that darkens the red, green, and blue values but the white don’t get darken, as it shouldn’t, and some natural colors don’t get darken as much, which is why the current shader looks slightly dark on parts of any image, rather than keeping some of the luminance that is similar to the screen. I played the GBA on various light source, many times, and I see the full range of red, green, and blue pops in a bit, and some contrast shows a bit more there too. Even though I explained about that, the gamma still varies from light source depending on the brightness, but the luminance sort of plays in. In normal play on the hardware, it would look a bit like the default 1.8 “light intensity” from the shader, if played on a lit place that isn’t lighted directly from a light bulb, or the sun unless full cloudy. It can sound complicated, but that’s how it kinda works. I never seen a research document on those type of screens. In conclusion, some of the colors are supposed to pop in due to the value of rgb from the hardware being lighter and retain a bit than natural colors.
I did a test of switching between display gamma and target gamma, and found interesting results. While keeping the display gamma to 2.5, which is the basis of the actual color value from each rgb captured directly from the GBA hardeare., results may vary, because parts of the image can pop out more than it should, depending on the target gamma, so I had to play around a bit. I will post interesting results when testing this for the next week. I did test by putting display gamma to 2.2, and target gamma to somewhere similar to the default settings on current shader, and it can be balance with colors popping out, and each rgb colors should retain the intensity a bit more, just like I explained about. I do apologize if it sounds a bit complicated, but I do try to keep the shaders more accurate to the hardware and comparing them. I should release the final results next week as a christmas release.
By the way, I did watch My Life in Gaming newest video, RGB 208 for Gameboy library and with GBA included. They showed off the screens of the GBC, GBA, and the GBA SP ags-001. Coury mentioned that the GBA has a bit darker screen luminance than on the GBC and SP 001. I know the SP 001 is exactly the same as the one from original GBA, since it has better glass protection, but for GBC, I see some slight difference in colors, and it looks a bit close to my shaders than what gambatte produces, but for now, at least the gambatte has a bit more contrast. I don’t own a GBC nor any flashcards for it to show raw RGB, so I don’t know how it would look in person right now. Coury also showed off the GBA Micro and said about the colors being washed out a bit when comparing with SP 101. It may share similar color gamut as for the GBA or NDS phat, but I don’t know since I don’t own that model either. The video is very interesting to watch, seeing the screens in action with more professional shoots.