PhotoShop Question :: Something I'm Not Understanding

Horoscope Fish

Senior Member
I opened this raw file from ACR and applied a Gradient Map and then a Levels Adjustment Layer. I pulled in the Whites slider to new value of 220 and bump the Blacks slider to a new value of 5. Histogram looks good to me with better contrast and no clipping; pretty much everything I want, nothing I don't:
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Gradient Map & Levels #1.jpg

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But... When I turn OFF the Gradient Map, the RGB Histogram clearly indicates there is significant clipping in the Highlights region:
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Gradient Map & Levels #2.jpg

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So now I'm thinking it's probably the Blue channel because of the scrim in the background. I open Histograms for the individual channels and my suspicion is confirmed... The Blue Channel is clipping pretty hard while Red and Green channels appear fine:
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Gradient Map & Levels #3.jpg

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What is confusing me is why the Histogram for the Blue channel appears to be so heavily blown out when, at least to my eye, the shot looks much better. Never in a million years would I look at that shot and think the Blue channel was clipping, neither in Luminance nor in Saturation... Yet according to the Histogram it is. ???
 

hark

Administrator
Staff member
Super Mod
Contributor
Which version of Photoshop are you using? Do you have a previous version installed for comparison?
 

hark

Administrator
Staff member
Super Mod
Contributor
I don't know how to check clipping of the whites in Photoshop, but can you send the file back to ACR and see where the whites are clipping? <Press and hold ALT on a PC while clicking on the Whites slider> Would that tell you?
 

J-see

Senior Member
I checked your shot (the screenshot) in AP and it shows the same clipping in the blue channel. There's a blue color cast in the shot which is why that blows out in the blue channel.

Screen Shot 2017-12-20 at 15.12.18.jpg

PS is correct even when the shot itself "looks" ok.
 
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Chucktin

Senior Member
I opened this raw file from ACR and applied a Gradient Map and then a Levels Adjustment Layer. I pulled in the Whites slider to new value of 220 and bump the Blacks slider to a new value of 5. Histogram looks good to me with better contrast and no clipping; pretty much everything I want, nothing I don't:
.....
View attachment 274369
.....
.....
But... When I turn OFF the Gradient Map, the RGB Histogram clearly indicates there is significant clipping in the Highlights region:
.....
View attachment 274370
.....
.....
So now I'm thinking it's probably the Blue channel because of the scrim in the background. I open Histograms for the individual channels and my suspicion is confirmed... The Blue Channel is clipping pretty hard while Red and Green channels appear fine:
.....
View attachment 274371
.....
.....
What is confusing me is why the Histogram for the Blue channel appears to be so heavily blown out when, at least to my eye, the shot looks much better. Never in a million years would I look at that shot and think the Blue channel was clipping, neither in Luminance nor in Saturation... Yet according to the Histogram it is. ???
First I wouldn't use a Levels Layer - use Curves, the effect is much grandular. Secondly check your order. It almost looks like the Levels is affecting the gradient map not the background layer.

Sent from my Pixel XL using Tapatalk
 

Chucktin

Senior Member
Thank you. I'm about 99% sure that's what's happening... Seems so obvious once someone else points it out.
Kudos to you for using a Gradient Map layer, something I've only fumbled at. As to the Layer Order it's kind of obvious once you think about it.

Sent from my Pixel XL using Tapatalk
 

Horoscope Fish

Senior Member
... As to the Layer Order it's kind of obvious once you think about it.
You know, I can make and refine selections like a boss, mask and map and duotone... Need help with your Blending Mode? I'm your guy.

But layer-order?

Yeah.. I'm not saying I face-palmed after reading your post, but I'm not saying I didn't, either.
 
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