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Old 03 May 2015, 01:48   #86
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Join Date: Jun 2010
Location: PL
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Originally Posted by jsr View Post
Well then, which IFF chunk do you suggest for copperlist storing?

Is dithering possible between two distinct images? Because if we quantize the image per N lines, those will be different images.
I would go for PCHG as most "standard" - Dynamic Hires and SHAM are usually less future proof (AFAIK Dynamic hires from NewTek not use Copper at all).

I understand that dithering is a way to distribute quantization error (and this can be tuned psycho-visually to make it less unpleasant) - see Ulichney paper also - i assume lines can overlap and as such good converter should verify interline correlation but generally yes - line or group of lines can be considered as independent picture but it will be good to do line/group of lines overlapping in a wise way.
This is same issue as for HAM - normal dithering will give suboptimal results as quantization will be distributed trough HAM principle and usually is no longer correct dither but new error source (naive approach is to propagate error more to vertical direction as lines can be full independent where HAM pixels are linked - they depend from previous value and because full transitions require 2+1 pixels - problems are unavoidable - wise CLUT may help but correct dithering will be crucial).
I still searching for details about proprietary STORM dither used by Moovid.
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