TL;DR - If you’re using an LED/LCD or Plasma display, then it is more than likely that the colors, brightness and contrast are not correct for playing retro video games, even if the display is calibrated. This is because the HD colorspace is different from what SD CRT TVs used. Using “Fudoh’s 240p test suite” resulted in a much better monitor calibration for emulating old video games than using any of the standard test patterns commonly available. Before you go altering shader settings, make sure your monitor is calibrated right if you want the best results possible. http://junkerhq.net/xrgb/index.php/240p_test_suite
So after what’s probably been weeks of messing around with shader settings, I finally discovered that the problem this whole time was the display calibration I was using. I hadn’t sufficiently considered that different calibrations can bring very different results. Previously, I did the “basic calibration,” which just involves adjusting the greyscale and selecting the right color temperature, by using the test patterns available at www.lagom.nl/lcd-test. Using these patterns, I found that leaving my display’s settings at their default values resulted in the greatest range of colors being displayed as well as the greatest range of blacks and whites. The only thing I changed was to turn off all the video processing crap in the advanced picture settings. This, however, looked absolutely terrible when playing SNES games through Retroarch. The picture was much too dim and bland, with insufficient color and contrast. Fiddling with shader settings was a fool’s errand; I could make one aspect of the picture look better only at the expense of another.
What I eventually came to understand, after much reading and experimentation, is that some displays just can’t hit every shade of black or every shade of white without looking overly dull/losing color. To put it another way, sometimes you sacrifice color accuracy for contrast ratio or vice versa. Very good displays don’t require this compromise, but most displays do to some degree. Thus, different calibrations produce different results depending on what the calibration is aiming for. For SNES games, maximizing the contrast ratio resulted in an overly dark image. On the other hand, maximizing the color range resulted in an image that was flat and dull, with bland colors. I tried calibrating the greyscale using the SMPTE patterns, which resulted in a brightness of 30 and a contrast of 100, which was way too dark for video games even with the backlight cranked up. The AVSHD patterns resulted in the same settings.
I finally solved my problems by using “Fudoh’s 240p NTSC Test Suite,” for the SNES, which is designed for use with the XRGB mini upscaling unit. I basically stumbled upon these settings “by accident,” but I think they are a vast improvement over anything I’ve tried to date.
With all my display settings at their defaults and the video processing crap turned off (AND doing the same for my graphics card settings), I first adjusted the brightness by using the “color bars” test pattern so that column 0 was black for all colors and the column between 0 and 1 just barely visible. This required being in a totally dark room with my eyes practically pressed to the screen, with post-it notes covering up the adjacent columns. Seeing the extremely faint shade of blue in the column between 0 and 1 was very difficult.
I then adjusted contrast by using the “gray ramp” test pattern. Standing a good distance away from the display, I kept increasing contrast while making sure I could still distinguish the two lightest shades of white. For my display, this meant adjusting the contrast all the way to 100%. I then went back to “color bars” and fine-tuned brightness further. Then I looked at the “pluge” test pattern and found that it looked exactly as it was supposed to when I selected “NTSC 7.5 IRE.” I then set my display backlight to 100% and then checked all three test patterns again to confirm that no further adjustments were needed. Seeing that red was looking a little brown in most games, I upped the color setting by increments of 5% until the colors looked oversaturated, and then adjusted down by 5% until they no longer looked oversaturated, arriving at a setting of 60%.
After making these adjustments, I loaded up Super Metroid, and applied the CRT-Hyllian-glow shader (by itself, not the preset) with Hyllian’s anti-ringing configuration enabled, sharpness at 2.0, scanline strength at 0.70, and everything else at 1.0. I started the game, and my jaw dropped – FINALLY I was seeing the color, contrast and brightness that I was looking for. I looked at several more games before concluding that I had basically nailed it. The total color range might be slightly reduced with these brightness/contrast settings, but it doesn’t matter because these games don’t display anywhere near the range of color that my display is capable of.
This might not be as good as a CRT in terms of color and contrast, but it’s close enough that I’m more than satisfied, and it’s probably the best it’s going to get with this display. At this point, I don’t see anything further I can do to the picture to improve it, whether it involves shader settings or display settings. I could get it professionally calibrated, but it isn’t worth it for this display. I’m not sure why the results are so much better using the test patterns from Fudoh’s 240p Test Suite than any other patterns I’ve used- perhaps because they are specifically designed to optimize the picture for 240p consoles using NTSC? For normal computer use or watching movies, I find the default settings are preferable (as confirmed by the Lagom test patterns), since they are more accurate in terms of color.
The lesson here is: make absolutely sure that you are using the optimum calibration for your display and for what you want to use it for before you go fiddling around with shader settings. Different calibrations/test patterns will result in different settings and different results. In my experience, using the test patterns found on “Fudoh’s NTSC 240p Test Suite” results in the best picture possible for emulating 240p consoles. I could have saved myself a lot of hassle if I had just made sure that my display calibration was good before attempting to apply shaders.
