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Old 09 August 2017, 23:10   #90
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Join Date: May 2017
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Posts: 330
Well, it's a lores shader. I'm sure guest can do a hires version too.
Well, it's lores with a good reason. I would need to use a slower interpolation algorithm for a hires version and the sound could/would crackle. Amiga emulation is special regarding this matter and classic crt shaders can't do a perfect job where hires makes sense (Lionheart etc.). But it's not that bad at all in general, though it/they (lores shaders) might require an extra startup configuration as it changes the default settings.

If I change to lores it works but I get a horizontal jitter of 1 lores pixel left and right of the disk hand and text, about twice per second.
Yeah such things can happen, jittering happens to me also with various CRT shaders if i include a mask on the WB screen. I can report it clean with the games i tested though.

To make CRT on LCD I need global desaturation to not have to lower the contrast
I understand this as a shift towards grayscale. There are some ways to achieve this, shouldn't be a hurdle.

exponential subpixel blur that I can adjust
The PD CRT-Lottes uses exponential blur which is adjustable. Worth taking a look.

raise the black point on odd lines (as in pixel lines, not scanlines "between" pixel lines), and then a mask (edit: for scanlines) can be applied that is as good as the monitor resolution is larger than the Amiga resolution.
Black point could be something new, didn't see it with popular CRT shaders. Scanline masks can be also tricky, they might require to use a constant vertical integer scale factor and could be applied in linear (not 2.2 gamma) space from my observations.

After that, there's a point in adjusting the gamma (which should be 2.2 for CRTs on LCDs but, you know, mileage varies).
Yea this shouldn't be a problem to code.

I left this as an option in the CRT-Scanline shader, it's a bendable rule and it didn't appeal to me in this case since i wanted a specific scanline look. Interpolation looks better with higher gamma and solid scanlines with lower. There is tiny bit of interpolation and a strong scanline presence so the scanlines won.

This is the recipe. Can you give me some pointers in the right direction to code that guest.r?
Sure, np. I guess you are more a WinUAE user. HiRes/LoRes doesn't matter too much, you can have both versions. You could start with a horizontal exponential subpixel filter, make lookups gamma correct, apply desaturation etc. You'll see WinUAE is quite specific, looking forward for that.
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