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Re: [OM] IMG: Friday Flower - Jim N.

Subject: Re: [OM] IMG: Friday Flower - Jim N.
From: Moose <olymoose@xxxxxxxxx>
Date: Fri, 10 Jun 2011 21:43:57 -0700
On 6/10/2011 5:45 PM, Jim Nichols wrote:
> The combination of late afternoon sun and the camera's color rendition
> changed the color slightly.  She is probably correct.

Jim, you've been doing a great job lately of avoiding blown highlights in red 
and yellow flowers.

What's happened here to make the color go wrong isn't the sun, at least not 
primarily so, nor the camera's inherent 
rendition. Actually, this is a great example for teaching. :-)

It's obvious at first glance that there is something 'off', esp. in the 
flowers. Seems like the colors are lacking snap, 
contrast is low, 'something'. If you look closer at the flowers, esp. at the 
larger size, there are large areas that are 
all just one color, very unnatural for flowers. Then I hear apparently the 
color is off.

That's all from clipping in one channel, in this case, the most common one for 
flowers, red. Take a look at the 
histogram. 
<http://www.moosemystic.net/Gallery/Others/Nichols/Mothers_Day_Basket_5_Wks_Later.htm>

The overall histogram doesn't look too bad, and that can fool you. The red 
channel is heavily clipped. That means many 
pixels have the same value, 255, for red, while green and blue are normal. What 
that does is make the red highlights 
less red than they should be, both relative to less bright reds and relative to 
the rest of the image.

It also loses tonal differences in the red highlights, so that the natural 
variations can turn, as here, into one, 
undifferentiated color.

As a side note, the same thing can affect shadows, giving them a color cast 
that isn't in the subject. Here, the shadows 
may be a little less blue than is accurate. But most people don't notice that; 
can you imagine Siddiq suggesting that 
the shadows are off in this image? It looks fine to me, too. We're looking at 
the flowers, anyway.

Moose
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