Again, thanks for those ideas, Moose.
I have checked that all my cameras use aRGB.
Chris
On 20 Apr 2014, at 22:37, Moose <olymoose@xxxxxxxxx> wrote:
> More about red channels and what happens when you convert color spaces. And
> why Joel may have done his orchids
> perfectly, yet I found clipped red channels in some.
>
> This expands on my last posted image comparisons by adding histograms.
> <http://www.moosemystic.net/Gallery/tech/BrowserColorSpaces/TulipH.htm>
>
> Color space conversion were done using Perceptual intent, which is, I think,
> why they all appear the same.
>
> Apparently, none of the colors, ACR default or after pretty strong LCE and
> Curves, exceeds the aRGB color space, so the
> ProPhoto and aRGB histograms are identical.
>
> But, in order to maintain the same appearance the sRGB conversions move the
> channels up toward the top. As this was shot
> at -2/3 EV, the ACR default version still doesn't clip. But the post version
> clips a fair amount.
>
> Soooooo ... If you convert from a larger space to sRGB as the last step, and
> don't check the histogram, or if you post
> in a gallery that converts aRGB to sRGB, most likely with a less
> sophisticated conversion engine, it's possible to have
> a clipped channel without knowing it.
>
> I was at first disappointed that this particular image doesn't show the
> effects of clipping. That it is not nearly as
> heavily clipped and the orchids certainly helps. The striations and other
> color variations also help it avoid that 'big
> blobs of one color without detail; effect that's common in red-orange-yellow
> flower images.
>
> Perhaps it's just as well, though. We've already seen the effect on a couple
> of Joel's web images. To not have it
> visible here shows how tricky these shots can be. And how proper technique in
> shooting and processing can avoid trouble.
>
> As shown in my previous post, one may avoid one big pitfall by posting aRGB
> JPEGs, at least for the huge majority of
> viewers using current version of the big four browsers.
>
> Unshorn Moose
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