Re: Color Conversions and Dither
Re: Color Conversions and Dither
- Subject: Re: Color Conversions and Dither
- From: Marco Ugolini <email@hidden>
- Date: Fri, 16 May 2008 12:48:03 -0400 (EDT)
Ken Fleisher wrote:
>Graeme and Martin, thanks for you interesting observations. I don't actually
>have any problem either using dither or not using it. I was just curious if
>others simply leave this option "on" all the time and whether anyone has
>experienced any negative side effects from multiple dithers. My guess is
>that most people leave dither turned on and don't have any problems as a
>result.
Ken,
You could do a test: perform a high number of conversions to and from a number of color profiles, starting from a relatively smooth and noise-free original, then compare the end result to the original to see how much noise is added and how it affects the image.
In the normal course of color workflows, you don't normally need to use the dither option if you keep your files in 16 bits. In 8 bits, it depends on the presence of noise in the file: if there is noise in it already, the use of the dither option may be redundant. If the 8-bit original is smooth and you've applied some strong tonal adjustments, then the dither option may help minimize possible banding.
I keep the dither option unchecked in my Photoshop color settings, and in any case I elect to use it or not at conversion time, in the Convert to Profile dialog box.
To be honest, I have not done any extensive testing myself of the effects of a repeated uses of the dither option. The choice of dithering as default is possibly not harmful, but probably not necessary either in most instances. How many times is an average files converted? If you use a late-binding workflow starting from a Raw file -- once, really, from the original RGB space to the final output space.
I would say, whenever possible, try to avoid doing any harm to the file (a sort of "digital Hippocratic Oath" <g>). Use the dither conservatively -- only if you can see a beneficial effect.
Marco
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