Why is my photo partially colour imbalanced?

Question

I have this photo where part of it is funnily colour imbalanced. I took some product shots under couple of 5500K lights. Part of the product was navy blue and it is appearing as black in the raw files.

I could bring this back to navy blue by just turning the colour temperature slider down a little bit in Lightroom, but this imbalances the rest of the products and the entire image because they are completely colour corrected.

Can someone explain why a partial image might have an out of whack colour temperature and rest of the image is fine? I always make sure the colour balance in the camera is set correctly.

Also for now, I have used the adjustment brush to colour correct part of the image but I am more interested in to why this actually happened and if there is any in-camera or lighting solution to this.

Answer 1

There may have been CRI issues. The lights are slightly yellowish, so have a relative deficit of blue. Since the hat is already dark, it doesn't reflect as much blue as you would have liked.

Your white balance may also have been off just enough to affect the appearance of the hat. Objects reflect and absorb light, so the lighting in the scene isn't quite the same as before objects were added. Try setting up the scene first. Then set custom white balance with the white reference placed directly over the hat.

Camera color profiles may have affect the appearance of the image. Some related questions:

• Why does my subject's skin have such a red cast — did my auto white balance fail me?
• How to stop my camera from exaggerating differences in skin colour?

For post processing, my approach was slightly different from yours. It might be easier than using an adjustment brush. I adjusted levels globally with color layer blending. Other colors in the scene were affected, but possibly by an acceptable amount.

Answer 2

Take a look at this question: Do I always get the same colours when I set the white balance correctly?

Some cameras have different sensitivities to colors, and to tones.

Some light has different wavelengths, and make "white" with different combinations of them.

in-camera or lighting solution to this.

Yes and no. It is a process. On the lighting side, make sure your lights have a good color rendition index. CRI. Most flashes do, but most LED lights do not. If you are using LEDs, look for a CRI above 90; 95 is a nice number.

But as I explained in the other answer you need to color calibrate the process.

That is why you need a color reference chart, to make a color profile of your camera+lens+LightSituation.

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One thing I recommend is making the white balance based on the source light, especially if you are only using one big softbox. Color issue: studio images have a pink hue Measuring your source light gives you an exact color balance.

Sometimes your white paper is not white. Try different types of paper to find the whites one.

After doing this search, only then, use the white paper as white balance as the last resource.

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One additional thing. Color temperature is not the only issue, it only affects the color in one axis, and remember that color, in general, is a 3Dimensional space, not a linear one.

Answer 3

This is probably to do with the relationship of your shutter speed to the frequency of the AC electrical supply to the lights.

See this article for a detailed explanation.

Essentially, if you can have your shutter open for at least the length of the AC cycle (eg 60Hz = 1/60 sec), you should be able mitigate the problem.

I've experienced exactly the same issue shooting gymnastics competitions under fluorescent lighting, and it's very difficult to strike a balance between freezing the action and dealing with changing colour temperature across the frame.

Given that you're shooting product shots (presumably on a tripod), it's probably easier for you to work around the issue than in my scenario.

You will still want to shoot raw so that you can consistently apply white balance correction across your different images.