Re: Digicam, sRGB and Photoshop
Re: Digicam, sRGB and Photoshop
- Subject: Re: Digicam, sRGB and Photoshop
- From: Graeme Gill <email@hidden>
- Date: Wed, 27 Aug 2003 11:50:53 +1000
Jarkko Viljanen wrote:
>
- And yes, I recall YCC form PhotoCD, too. Did YCC have something to do
>
with TV-technology, as PhotoCD was originally meant to be viewed via a
>
TV set?
Not directly. Systems that aim to compress images (like TV, JPEG, PhotoCD),
take advantage of the fact (stated loosely) that human vision has less
spatial resolution in the color component, and greater in the luminance component.
By converting to a luminance, red/green, yellow/blue type colorspace, the color
components can be downsampled to a lower resolution, with little visual
effect. JPEG and PhotoCD sample the color components at 1/4 the total
resolution of the luminance components. TV encodes the color component
on a lower bandwidth, sub-carrier based channel within the higher
bandwidth luminance channel.
[YCC for a "raw" format sounds like an oxymoron. It can't be raw if
you've attempted to convert to a standardized color space.]
Graeme Gill.
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