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Help needed on research project. Can Photoshop do this? We think not.


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Dear Photoshop Guru forum users,

My name is Martin Constable and I am research professor at Nanyang Technological University in Singapore. I have a problem that, hopefully, will present something of a challenge. We are working on the topic of hue contrast, which is something that we feel Photoshop isn't very good at. What is hue contrast? Consider a tree whose leaves range in hue from blue-green to yellow-green. A hue contrast stretch would pull these values out so that they extend fully from yellow to blue. A hue contrast compress would reduce the range of hue values to a single value (e.g. all blue-green).

The attached two images hopefully show what I mean. These were made using software that we are developing and we would love to have the help of the Photoshop community in testing our assumption that Photoshop is not able to perform such functions. Our challenge: using Photoshop, can anyone reproduce our results? The original (rather large) files are here:

Hue contrast compress target:
http://dl.dropbox.com/u/3788380/compress_target.tif.zip

Hue contrast compress result:
http://dl.dropbox.com/u/3788380/compress_result.tif.zip

Hue contrast spread target:
http://dl.dropbox.com/u/3788380/spread_target.tif.zip

Hue contrast spread result:
http://dl.dropbox.com/u/3788380/spread_result.tif.zip

Stretch.jpg

Compress.jpg
 
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Ivan Skoro

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I think this is possible if we have RAW files.
Also, maybe someone more experienced could play with the color settings. There's a slider for practically any color. I think this is easily achievable in Photoshop.
Could you please upload the image to dropbox for instance? I can't save it.
 
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Thank you greatly for your feedback,

My understanding of Photoshop's ability to manipulate hue is this:

1. That a hue value can be made to seem more intense by editing its brightness and/or saturation.
2. That the hue values of an image can be cycled i.e. the color wheel rotated.
3. That a particular hue can be imposed onto an image e.g. everything made more red.

However, I can see no easily available way to spread or compress the local hue values in the way that we are doing. Caveat: in the case of contrast compression it might be possible to go into the image and change every value arbitrarily to match the target values. It might also be possible to re-value the region them by brushing on new values using a layer blend (e.g. Hue blend mode). However, these are not procedural approaches (e.g. it is posible to select a color range by individually selecting each component pixel). We need to identify a procedural approach e.g. something from the filter or adjustments menu (though frankly if you can do this in any way at all we are interested to know how).

If you can reproduce our results I would LOVE to see how you did it. Here are the dropbox links:

http://dl.dropbox.com/u/3788380/compress_result.tif
http://dl.dropbox.com/u/3788380/compress_target.tif
http://dl.dropbox.com/u/3788380/spread_result.tif
http://dl.dropbox.com/u/3788380/spread_target.tif
 

Ivan Skoro

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No problem.

Again, the same. Images are opened with QuickTime, and I have to buy a pro version so I can download an image. I don't understand. Could you zip just compress result and target?
Also, do you have a RAW file?
 

Stric9

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Forgive me for stepping on the stage with a University Professor for I am by no means worthy to be speaking in such company. I am primarily self taught in Photoshop, so my ignorance may quickly come to light.

My questions are these. Do these original images not properly represent the realities they portray? And if not, then doesn't it make more sense to look at improving the capture process rather than expanding or contracting the hues once they are captured? In expanding the hues you have these magenta reflections on the water that to me seem to be unnatural and don't reflect the reality that is just beyond the bank and in the sky.
11.JPG

Just my thoughts, however, silly they may be.
 
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Forgive me for stepping on the stage with a University Professor for I am by no means worthy to be speaking in such company. I am primarily self taught in Photoshop, so my ignorance may quickly come to light.
Dude... I'm just a joe. Self taught also... and still learning :)

My questions are these. Do these original images not properly represent the realities they portray? And if not, then doesn't it make more sense to look at improving the capture process rather than expanding or contracting the hues once they are captured? In expanding the hues you have these magenta reflections on the water that to me seem to be unnatural and don't reflect the reality that is just beyond the bank and in the sky. Just my thoughts, however, silly they may be.
As our process is a filter, unwanted color adjustments on non-target regions are bound to appear. One of the problems with photographing such things as jungles, desert floors, rocky terrain etc is that the camera is not very capable of capturing their huge range of values. This, as you noted, is a current limitation of the capture device. Why are we not trying to improve this device? well... my passion has always been in what can be done post-capture. I trained as a painter and I was brought up to see the scene as just a 'starting point' which the artist can anywhere they want. Is this a folly? Well, all research projects have a right to fail. Time will tell.
 

Steve

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I'm confused too.
The eye shows something and the camera captures it.

Tis color can be measured.
I don't see you "pulling yellow green from blue green"

You've just manipulate some greens to lean yellow.
So what is the point you're trying to make?

I can do that in PS.
 

ibclare

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I think the color stretched image loses a lot of color contrast, from the trees to the water, so I think you have a bit of work to do. But it's an interesting concept and the results too.
 
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You've just manipulate some greens to lean yellow. So what is the point you're trying to make?

I can do that in PS.

It is clear that I have not explained myself very well. Apologies. Here is a schematic showing what I mean by hue contrast compression and expansion:

test.jpg

Here also is some more of our results.
Results of Hue Stretch

Essentially, we are taking a discreet slice out of the hue spectrum and compressing or stretching it. It is possible, in photoshop, to select a color and perform an edit on that color. But to do it on a range is very difficult. If anyone thinks it is easy I would love to see the original file.
 

Ivan Skoro

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Nope, this can't be done in PS, at least I can't do it.
I think this is interesting, but I don't see the point in making a new software just for this. Have you considered selling this as a PS plug-in?
 
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Nope, this can't be done in PS, at least I can't do it.
I think this is interesting, but I don't see the point in making a new software just for this. Have you considered selling this as a PS plug-in?
Thanks. It is good to know that it is a challenge. None of us yet are anywhere near thinking of this as a comercial venture. We we be looking for people to play with a prototype as soon as we have one (our current version only works within a specific developer environment).
 

jn4u

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This is the way I do it.

To get more color variation in a picture. I convert the picture to LAB. Put on a Curve Layer. Put a pivot point in the L channel. One point in the A channel and in the B. Bend the cure to drive the colors apart. “Man from Mars” and is develop by Dan Margulis.

The second method is to use a plugin called curvemeister dot com, Its has all the channels and also the hue “color mode”, that u are able to put a s-curve in the hue channel to drive the colors apart. To get more color variation.



It take no big time.
 

Furio

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I have studied all the images that the professor provided and all the images on pages that he linked to and in every case the result was just bad. It becomes even more noticeable when I push the contrast to the extremes in LAB mode of both original and filtered images. In that context I find it odd that we're being asked to find a way to achieve those same (bad) results. That's the problem I have with the whole idea; I haven't seen any benefit at all. I'm a visual guy, I've developed a keen eye for these things and I just want to see an image that visually got better. Even going by the actual numbers, I still see no improvement at all, only images that have their quality degraded.
 

jn4u

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Well think the idea is good. It’s the same as bigger sensor in the camera. You are able to catch more color variation. Often I picture with 1 static colors in rain forest. I all the time has to drive colors apart with “man from mars” method. Fine tune the separation with curvemeinster hue cure and masks inside the tool.
I think that color man agent work flow is good. But I also think that how a camera sees a picture is not the same as a human. Simultaneous Contras, gestalt theory and more with human visual system. Its all depends on what we want to see.
 

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