Olympus-OM
[Top] [All Lists]

Re: [OM] A Redder Channel [was More Red [was 2014 Orchid Show]]

Subject: Re: [OM] A Redder Channel [was More Red [was 2014 Orchid Show]]
From: Chris Barker <ftog@xxxxxxxxxxxxxx>
Date: Tue, 22 Apr 2014 16:48:08 +0100
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

-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz