Creating a Hue Map

[Rich54]

@thebestcpu

John,
First question: a few weeks ago you created this Hue Map of the image of boats in a harbor (first attachment; OP was R.Braverman). Can you please tell me how you did this?

Second question (and anybody is free to answer): In an entirely unrelated tutorial (for identifying blemishes and noise), I came across a technique using an extreme zig-zag Curves adjustment (shown below). Just for fun, I applied it to the boat image. It's an interesting effect and I like it—it sort of looks like colored pencils—but I'm not sure that it's useful for anything. Does anybody know if this zig-zag curves adjustment represents any known technique or application? I'm not sure how to think about exactly what the curves adjustment is doing.

Rich

 

[thebestcpu]

@thebestcpu

John,
First question: a few weeks ago you created this Hue Map of the image of boats in a harbor (first attachment; OP was R.Braverman). Can you please tell me how you did this?

Second question (and anybody is free to answer): In an entirely unrelated tutorial (for identifying blemishes and noise), I came across a technique using an extreme zig-zag Curves adjustment (shown below). Just for fun, I applied it to the boat image. It's an interesting effect and I like it—it sort of looks like colored pencils—but I'm not sure that it's useful for anything. Does anybody know if this zig-zag curves adjustment represents any known technique or application? I'm not sure how to think about exactly what the curves adjustment is doing.

Rich


View attachment 149416


View attachment 149417

Hi @Rich54

I posted the Action I use for Hue Maps here: https://www.photoshopgurus.com/forum/threads/hue-map-action.80709/

It's a more efficient Action to create a Hue Map than the one I made in ancient times
John Wheeler

 

[thebestcpu]

@Rich54, do you have a link to the topic about the zig-zag curves adjustment? I do believe I can explain what is going on, yet I want to match that to what you read.
Or better yet, save the curves adjustment Layer to a file and attach it in another post.
John Wheeler

 

[thebestcpu]

Hi @Rich54

Here is a walkthrough of what is going on with that curves adjustment Layer.

Here is the starting image I used:



I applied a curve adjustment layer with linear edges, all going in the same direction (just zigs). I did this with the pencil tool in the Curves Adjustment Layer.



The following is the same image with overlay annotations:


I annotated seven zones of input values (x-axis) in alternating blue and cyan in the above image.
This Curves adjustment Layer takes the RGB values in its particular zone and amplifies those colors in that zone maximizes contrast in the zone.
The image pixels in each of their particular zone are contrast amplified in the same fashion for all several zones.

The next image shows when I take the curves in just the cyan zones and invert them:



Following is the annotate version:



So, the pixels were inverted or made into a color negative for those alternating cyan zones.

So what is going on is the pixels that originated in the blue zones are maxed out in contrast to that zone.
The pixels originating from the aqua zones are also maxed on in contrast and in addition color inverted.

The only difference between the above and the solar curve is that the zone transitions are smooth.

I hope that helps you understand what is going on.

John Wheeler

 

[Rich54]

John,
Thanks for the reply. I saw your action file for creating a Hue map. In my 17 years of Photoshop use, I have actually never used or investigated actions, so I'll first need to brush up on them to make full use of your attachment.

Regarding the zig-zag curves adjustment, I'm attaching a tutorial showing where I first came across it. This is a fairly straightforward tutorial for eliminating dust and scratches. The zig-zag curves technique is mentioned at 4:30 in the video. It is simply a temporary measure to create extreme color separation as a visual aid for identifying imperfections that might otherwise be missed at normal viewing. I tried it for fun on several images and I always seem to like the result. It's like a child's coloring book... if that child were taking LSD.

There's a lot going on in your detailed explanation of the curves adjustment, so I'll have to read it carefully a few more times to fully absorb it. Thanks again for the reply.

 

[thebestcpu]

Hi Rich
If you need any help loading and using the Action, just ask.
Also, many techniques are born of accident, and I bet zig-zag was one of them. I probably had some interesting images with the wild swings of the Curves Adjustment Layer and then noticed some uses along the way.

Not too different from the Hue Map. I was investigating the details behind all the blending modes, including those of Hue, Color, Saturation, and Luminosity, for my learning and possible uses. When I ran the Hue map and another Action to pull out just the saturation component, the JPEG artifacts stood out.

It helps identify images that have been compressed, even after compressing somewhere, and then saved as PNGs or TIFFs, etc. Many types of post processing (especially shifting of Hue, Color, and Saturation) will make the artifacts pop out—a good heads up to ask for a better original if available.

John Wheeler