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Weird B&W conversion issue

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John Little

Active Member
Premium Classic Member
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Jul 6, 2012
Messages
207
Lightroom Experience
Intermediate
Lightroom Version
Lightroom Version Number
Classic 9.2.1
Operating System
  1. Windows 10
I tried to convert an image in the Develop module to B&W, and a color adjustment came through in the final image. Here are the steps, with screenshots below:

1. Edit the photo extensively. A B&W conversion of this was B&W.
2. Make a virtual copy (the issue described below also arose on the original). This is the result:
veins--1.jpg
3. Apply a gradient--in this case, to make the orange color on the left side more similar to that at the right. I overdid it in the example to make the problem more obvious in the next step. In this gradient, I used the color picker and picked multiple orange hues, then increased the saturation, giving this:
veins--2.jpg
4. Convert to B&W using the button in the "Basic" panel. The resulting image shows an orange cast where the gradient was applied. It should be all B&W. What's going on?

veins--3.jpg

Maybe this is a job for Photoshop, if I only could figure out how to do it. But it seems like LR is misbehaving.

Edit: The same color cast appears when I use any of the B&W presets that come with LR.
 
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The B&W conversion takes place before anything else, regardless of the order in which you applied it. That means that you added a colored gradient to a B&W image.
That explains why I got this result, but how do you know that this is the order of operations? Not trying to be snarky; this is something I didn't know. I gather that the order of moving sliders doesn't matter, but I have to wonder why the B&W takes place first, and how many other times having this conversion take place first can have unwelcome but less obvious side effects like this.
 
The profile determines the raw conversion, and the choice for color or B&W is part of that. All other edits are made on the rendered result of the raw conversion, so after that choice.
I'm starting to understand. In case it makes a difference, this was a JPG from my pre-raw days. And I still wonder whether related issues might be affecting other images in ways that aren't so obvious to the eye.
 
My point was that you referred to a "raw conversion", which (to my limited understanding) doesn't take place with a jpeg.

Perhaps someone else can try to answer my question about whether this issue can occur with other types of edits besides the color gradient I applied.
 
My point was that you referred to a "raw conversion", which (to my limited understanding) doesn't take place with a jpeg.
No, raw conversion (demosaicing) does not take place for a jpeg, but everything else is the same in the same order.

Perhaps someone else can try to answer my question about whether this issue can occur with other types of edits besides the color gradient I applied.
Thank you, I'll shut up then.
 
Johan is spot on. If you apply a color in a local adjustment tool, it'll do exactly as you ask and add that color. Some people use it as a way to hand color B&W images. What other kind of scenarios are you considering?
 
Johan is spot on. If you apply a color in a local adjustment tool, it'll do exactly as you ask and add that color. Some people use it as a way to hand color B&W images. What other kind of scenarios are you considering?
Thank you for a more general response to my question! I'm not trying to be snarky (sorry Johan), but to understand how I went wrong and where else I might go astray. This seems to cover the issue with the color adjustment, and perhaps there are no other scenarios where an adjustment, local or otherwise, will give unwanted results. I don't have anything specific in mind, just wondering whether there are other cases that would give such behavior.

However, it's puzzling that if I make a global color adjustment on a color photo converted to B&W, using the "B&W" panel, I don't see any color in the B&W image. Obviously the color info is still present, or this adjustment wouldn't work. I don't really understand why it's different for a local adjustment, but as they say, "it is what it is".

For global adjustments, the HSL/Color panel offers a wide range of tools available to adjust the color. A few years ago, I asked in this forum why the same set of color adjustments wasn't available for local adjustments. The response (I think from Johan, in fact) was that I could do some of the same things using the Range Mask controls (for color or luminance). That's what I tried to do in this case, and got the color cast. I still wonder why the HSL/Color panel isn't available for local adjustments. Maybe it's too difficult to encode.
 
Johan is spot on. If you apply a color in a local adjustment tool, it'll do exactly as you ask and add that color. Some people use it as a way to hand color B&W images. What other kind of scenarios are you considering?
Can you point me to resources that discuss this in more detail? I tried to search your book for "local adjustments" and got stuff like "log" and "location", so that didn't work. I didn't see anything in the "Local Adjustments" section.
 
I've been mulling it over and I think the Color slider is the only one. Whereas all of the others are adjusting colors and tones within the photo, the Color slider actually paints on a color tint of your choice. It doesn't have a global equivalent. I don't think I referred to hand tinting in the book, but imagine you have an old B&W image from 100 years ago... you could use Color to paint on a skin tone, then a dress tone, etc.
 
I've been mulling it over and I think the Color slider is the only one. Whereas all of the others are adjusting colors and tones within the photo, the Color slider actually paints on a color tint of your choice. It doesn't have a global equivalent. I don't think I referred to hand tinting in the book, but imagine you have an old B&W image from 100 years ago... you could use Color to paint on a skin tone, then a dress tone, etc.
Thanks, my mind is at rest now!
 
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