Old 02-28-2018, 03:37 PM   #1
cyberdoctorind
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Default Need Help on Understanding Color (Hue) in a Photograph

I am trying to learn the nuances of post processing photographs and one of the tripping points always has been the Poor Color / Hue. I have recently got a rejection http://www.railpictures.net/viewreje...57&key=2273277 and I am looking for help in fixing this color cast issue along with an explanation on how to get the color cast proper.

Thanks in advance
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Old 02-28-2018, 04:58 PM   #2
KevinM
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Most often, when you see a rejection like that, it is because the color balance (often called "white balance") is significantly off (from reality), or because the image has an overall color cast (a bluish, yellowish, greenish, etc). There are a variety of ways in which this can happen, ranging from having the wrong color temperature set in your camera, to some post-processing step. Even the "AUTO" white balance setting in your camera can sometimes get it wrong.

A few suggestions:
  1. If you are shooting raw, there are settings in Adobe Camera Raw (ACR) that will allow you to adjust the color temperature and tint. If the image is too blue, you can raise the color temperature and if it is too yellow or warm-looking, you can lower it. If the image looks reddish you can bring down the TINT slider. If it looks too green, you can bring it up. Adjusting these things manually does require a little experience.
  2. An easier way to make an adjustment is to look for the "Remove Color Cast" feature in PhotoShop or PhotoShop Elements. That's an eyedropper tool that you can touch to some element in the image that should be black, white or gray. It's an automatic adjustment, so you cannot fine-tune it, but you can undo it if it does not look right to you. You can also try picking a different color target (black, white, gray) and see if it gives you better results.
  3. A third possibility is to use the "Auto Color Correction" option. Again, this is an automatic adjustment and you cannot fine-tune. I don't recommend this option, because when I try it, I generally don't like the results. Be careful with "Auto" adjustment options, because they can actually CAUSE color casts. In PSE, for example, I find that Auto-Levels and Auto-Smart-Fix tend to turn images too green. I don't like or use these options very often.

On most images, you can find something black, white or gray to help you make adjustments, but that's not always the case. There are some images which are indeed difficult to correct, and as noted, experience really helps.

Just make sure that the White Balance on your camera is not set to some wacky value. That will definitely cause your pictures to have color casts. Fortunately, if you are shooting, raw, it is correctable. If you shoot only JPEGs, having the White Balance set incorrectly will make your image very difficult to correct.
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Old 03-01-2018, 01:51 AM   #3
cyberdoctorind
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Quote:
Originally Posted by KevinM View Post

A few suggestions:
  1. If you are shooting raw, there are settings in Adobe Camera Raw (ACR) that will allow you to adjust the color temperature and tint. If the image is too blue, you can raise the color temperature and if it is too yellow or warm-looking, you can lower it. If the image looks reddish you can bring down the TINT slider. If it looks too green, you can bring it up. Adjusting these things manually does require a little experience.
  2. An easier way to make an adjustment is to look for the "Remove Color Cast" feature in PhotoShop or PhotoShop Elements. That's an eyedropper tool that you can touch to some element in the image that should be black, white or gray. It's an automatic adjustment, so you cannot fine-tune it, but you can undo it if it does not look right to you. You can also try picking a different color target (black, white, gray) and see if it gives you better results.
  3. A third possibility is to use the "Auto Color Correction" option. Again, this is an automatic adjustment and you cannot fine-tune. I don't recommend this option, because when I try it, I generally don't like the results. Be careful with "Auto" adjustment options, because they can actually CAUSE color casts. In PSE, for example, I find that Auto-Levels and Auto-Smart-Fix tend to turn images too green. I don't like or use these options very often.

On most images, you can find something black, white or gray to help you make adjustments, but that's not always the case. There are some images which are indeed difficult to correct, and as noted, experience really helps.

Just make sure that the White Balance on your camera is not set to some wacky value. That will definitely cause your pictures to have color casts. Fortunately, if you are shooting, raw, it is correctable. If you shoot only JPEGs, having the White Balance set incorrectly will make your image very difficult to correct.
Thank you Kevin, I guess it will take me a little practice to clearly identify the color casts. I have made a mental note of your points and will scrutinise my photographs for color casts going forward.
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Old 03-01-2018, 08:21 AM   #4
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Originally Posted by KevinM View Post

[*]An easier way to make an adjustment is to look for the "Remove Color Cast" feature in PhotoShop or PhotoShop Elements. That's an eyedropper tool that you can touch to some element in the image that should be black, white or gray. It's an automatic adjustment, so you cannot fine-tune it, but you can undo it if it does not look right to you. You can also try picking a different color target (black, white, gray) and see if it gives you better results.


On most images, you can find something black, white or gray to help you make adjustments, but that's not always the case. There are some images which are indeed difficult to correct, and as noted, experience really helps.
A method that IS variable: some versions of Windows have a "color enhance" feature (8.1 and maybe 7). This can enhance a selected color, but can also variably desaturate that color.
Yesterday I tried it on a snow scene with a difficult color cast. Selecting a snow patch and desaturating fixed not only the snow, but the overcast sky as well.
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Old 03-01-2018, 06:25 PM   #5
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I think I see you solved it? Looks brighter, what else you did? Looks like some white areas to use Kevins hints. Daylight photos should not be too hard as you have a single light source.

In addition to Kevin excellent rundown I like Auto Tone and in PS when you use these auto adjusts, you can go back and fade the effect just like you were using layers.

Some times a "little" negative vibrance slider helps also.

My personal feeling is on just regular photos they are a little too strict but on more "creative" ones they allow a lot of leeway. Blue Hour is a good example of that, it is a desirable look so they allow a cast well beyond normal.

Bob

Last edited by RobJor; 03-01-2018 at 06:28 PM.
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Old 03-05-2018, 04:00 AM   #6
cyberdoctorind
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Originally Posted by RobJor View Post
I think I see you solved it? Looks brighter, what else you did? Looks like some white areas to use Kevins hints. Daylight photos should not be too hard as you have a single light source.

In addition to Kevin excellent rundown I like Auto Tone and in PS when you use these auto adjusts, you can go back and fade the effect just like you were using layers.

Some times a "little" negative vibrance slider helps also.

My personal feeling is on just regular photos they are a little too strict but on more "creative" ones they allow a lot of leeway. Blue Hour is a good example of that, it is a desirable look so they allow a cast well beyond normal.

Bob
Yes Bob, I have started using Auto Levels in Affinity Photo and then go from there. I still am yet to get one photograph approved where the WB leans more towards warm (Eg, a warm sunny morning) but again as you mentioned, looks like regular photographs will not be extended this privilege. I am slowly realising the concept of rejections and trying my best not to repeat the same mistake for a subsequent rejection.
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