Correcting Colour Cast

[Tafflad]

HI ... for a number of years I have followed the Bob Arlen / Mandrake method of correcting Red Colour cast ... either manually or with the ATN script.


I have just upgraded my PC to Windows 7, Photoshop CS5.5 ... and with several hundred UW pics to catch up on thought I would ask advice.

Having been away from imaging for a couple of years, thought I would check on what is the current ‘best workflow approach’ to colour correction.
Majority of my images are 6 Mpixel jpegs, most without a strobe ... and many are typically deep, esp the wrecks.
All the things that make for lovely blue cast. :depressed:

I Googled around and see a couple of posts that comment that the Channel Mixer in Photoshop has made a huge difference to correcting UW images ? .............
Such as Photoshop: Underwater color correction - YouTube

Is there an updated ‘best approach’ method ? ... or any new or updated article ?

I have the Underwater ATN from Adobe site, (2010)
Bob’s ATN script (2004)
And the d8rRedV1p plugin

 

[Quero]

For jpegs, my favorite method is to use the 'threshold' feature.

1. You open 'thresholds' and move the slider at the bottom of the bar to one side or the other until the image is all white with a few specks of black or all black with a few specks of white.
2. Once you've got one of these, you select the 'colour selection' eyedropper and click on the black/white specks. You'll get a number 1 at the area you click on.
3. Then repeat the process going in the other direction (mostly white or mostly black), using the colour selection tool again to select the other color of the specks and leave a number 2 there.
4. After that, close and discard the thresholds feature so that you can see the color image.
5. Go to the 'levels' feature, and with the black eyedropper click on the number labeling the black speck or the white eyedropper to click on your white speck. Repeat with the opposite color.
6. Your colour cast should now be close to correct.

 

[Tafflad]

For jpegs, my favorite method is to use the 'threshold' feature.

1. You open 'thresholds' and move the slider at the bottom of the bar to one side or the other until the image is all white with a few specks of black or all black with a few specks of white.
2. Once you've got one of these, you select the 'colour selection' eyedropper and click on the black/white specks. You'll get a number 1 at the area you click on.
3. Then repeat the process going in the other direction (mostly white or mostly black), using the colour selection tool again to select the other color of the specks and leave a number 2 there.
4. After that, close and discard the thresholds feature so that you can see the color image.
5. Go to the 'levels' feature, and with the black eyedropper click on the number labeling the black speck or the white eyedropper to click on your white speck. Repeat with the opposite color.
6. Your colour cast should now be close to correct.

I'm missing the stsrt of this ..

Open up 'Thresholds' where ? .. on what tool ?

 

[Quero]

In the main menu bar there is a tab called IMAGE, and within that ADJUSTMENTS and within that THRESHOLD... When you open Threshold... you get a small window that has a triangular slider at the bottom.

 

[Tafflad]

For jpegs, my favorite method is to use the 'threshold' feature.

1. You open 'thresholds' and move the slider at the bottom of the bar to one side or the other until the image is all white with a few specks of black or all black with a few specks of white.
2. Once you've got one of these, you select the 'colour selection' eyedropper and click on the black/white specks. You'll get a number 1 at the area you click on.
3. Then repeat the process going in the other direction (mostly white or mostly black), using the colour selection tool again to select the other color of the specks and leave a number 2 there.
4. After that, close and discard the thresholds feature so that you can see the color image.
5. Go to the 'levels' feature, and with the black eyedropper click on the number labeling the black speck or the white eyedropper to click on your white speck. Repeat with the opposite color.
6. Your colour cast should now be close to correct.

I'm, not following this ... open image
Go to image > adjust > threshold

I get a histogram and a slider ... I can slide left or right, but there are no other tools active with this window ...
Not like the 3 'eyedropper' you get with leveles for example.

Or do you mean make theshold selection ... then close the threshold window ? .....
If so what tool are you opeiening to get at 'color' eyedroppers ?


Sorry if I'm being thick

 

[Quero]

It's easier to demonstrate than it is to explain....

So now you've got the threshold pane with the slider... slide the little triangular handle until you see only a few specks of either black or white (depending on which direction you slide the handle.

Go to the tools toolbar. In it one of the options is an eyedropper. Within the eyedropper there are two different eyedroppers--select the "Colour Sampler" one

Now take that eyedropper to the pane in the threshold window and click it on one of the specks. It will place a number 1 at the location

Next slide the handle the other way to get the specks of the opposite end of the spectrum and click the eyedropper tool onto one of those specks. It will place a number 2 there.

When you close the threshold pane, those numbers will still be on your image, so you can now open levels and use the black and white eyedroppers to tell PhotoShop that those places are meant to be black and white. It will adjust all the other colors for you.

Come back to Thailand and I'll give you lessons on digital darkroom, LOL.

 

[DevonDiver]

Here's my walk-through:

5 Minute Photoshop Edit for Underwater PhotographsScuba Tech Philippines

 

[Tafflad]

It's easier to demonstrate than it is to explain....

So now you've got the threshold pane with the slider... slide the little triangular handle until you see only a few specks of either black or white (depending on which direction you slide the handle.

Go to the tools toolbar. In it one of the options is an eyedropper. Within the eyedropper there are two different eyedroppers--select the "Colour Sampler" one

Now take that eyedropper to the pane in the threshold window and click it on one of the specks. It will place a number 1 at the location

Next slide the handle the other way to get the specks of the opposite end of the spectrum and click the eyedropper tool onto one of those specks. It will place a number 2 there.

When you close the threshold pane, those numbers will still be on your image, so you can now open levels and use the black and white eyedroppers to tell PhotoShop that those places are meant to be black and white. It will adjust all the other colors for you.

Come back to Thailand and I'll give you lessons on digital darkroom, LOL.

Mayve it will have to wait until return trip to Thailand.

When I open Threshold window, I can move slider. ... but I cannot select any tools ... only way I can select 'color sampler' is by closing the Treshold window.
I can then drop a '1' on a dot ... but I cannot move slider (window is not there), if I reopen Threshold window the slider tool is locked and will not move. ?

 

[Tafflad]

Here's my walk-through:

5 Minute Photoshop Edit for Underwater PhotographsScuba Tech Philippines

any chance you could make that downloadable ? maybe as a tutorial ?... or put a 'print version' button on screen.

Be good to have a hard copy as I run it through some pics ....
If I try printing all the other menus etc get printed.

 

[bullshark]

I have just upgraded my PC to Windows 7, Photoshop CS5.5 ... and with several hundred UW pics to catch up on thought I would ask advice.

You have the wrong tool,IMO.

Photoshop is a pixel editor for creating fantasies or compositing photos - Nice for HDR and studio stuff; not so much for underwater stills. It'll do what you need eventually though much harder than it should be...

Lightroom is a digital photographic development tool. Even though your photos are jpgs, you can still adjust the white balance which will remove the cast. Seconds per photo; one operation. You can also use the tools to adjust many other facets of the photograph much more competently than CS5. Meanwhile its the best photo organizer around.

If you had the cheaper PS Elements, you could use menu/Enhancements/Adjustments/Remove Color Cast. With that, just use the picker to sample the whitest thing you can find in the foreground and presto job done. If you can't find something white, something black will do or even neutral colors...just sample things until you like the result.