101–110 of 203 posts
With HDR and wide gamut on the horizon, things are moving even further away to ever requiring any form of dithering. You still need dithering to prevent visible banding in really subtle color gradients.
Is it just my eyes or does the gradient dithered in sRGB look more accurate that the one dithered in linear space?
Basically I'm afraid the author of this post is a bit of a "careless eager student" archetype who, while generously pointing out the gotchas that to an expert might be second nature, is also introducing unintentional errors that add some confusion right back.
I'm not expert in color, but with anything with soo many layers of abstractions (physical, astronomical, psycological, various models that approximate each), it helps to work symbolically as long as you possibly can so the work can be audited. Trying to correct from the current "baked" state is numerical hell.
Dynamic Rounding , developed by Quantel back in the 90s for digital video+film, is underappreciated. Dynamic Rounding + Blue Noise is severely underappreciated. https://en.wikipedia.org/wiki/Quantel https://patents.google.com/patent/US6281938B1
> According to Wikipedia, “Dither is an intentionally applied form of noise used to randomize quantization error”, and is a technique not only limited to images. It is actually a technique used to this day on audio recordings […] Dithering as a digital signal processing technique is also used frequently in the digital control of physical systems. One example of this is in the control of hydraulic servo valves[1]; the…
I would not define it exactly like that. I would say "Dithering is any method of reducing the bit depth of a signal that prioritizes accurate representation of low frequencies over that of high frequencies". This frames it as essentially an optimization problem, with randomn noise being a heuristic way of accomplishing it.
Read more at http://entropymine.com/imageworsener/
http://www.effectgames.com/demos/worlds/ http://www.markferrari.com/ .... I recall a recent kick-starter-type blog post about a work-in-progress game with huge 2d side scrolling dither art - can't find the link but :(
Video of Mark talking about his process https://www.youtube.com/watch?v=aMcJ1Jvtef0
My Dad! I can hear him talking about this...
With HDR and wide gamut on the horizon, things are moving even further away to ever requiring any form of dithering. You still need dithering to prevent visible banding in really subtle color gradients.
You still need dither for print, where subtle gradients on-screen can suddenly become very visible. I’ve had some large format giclee prints surprise me with nasty color banding.
Earlier quoted context omitted.
GIMP has it: Colors > Tone Mapping > Retinex
Ah thanks, just tried it out and it indeed produces quite a different result using that filter (default settings) before dithering. Here's a side-by-side comparison using an image from the front page of nytimes.com (be sure to click to zoom in for the full effect): https://imgur.com/a/mrHl7FW Without it (left), a photo remains "accurate" in terms of brightness levels. But with it (right), it becomes far more high-con…
I agree; the filtered image (right) is more aesthetically pleasing; but it feels much less accurate. It would depend on the intent of the image I think. If you're creating art, and using photographs in the creation, it's not a problem. If you're reporting on the world and just want to reduce the data size (or use a monochrome output medium), I wouldn't do it like this.
