How do I adjust colour casts between photos taken at different times?

Question

I have several photos of similar subjects on the same background.

As they were taken outside at different times, the lighting conditions are different, and so the colours in the photos aren't equivalent. For example, in some photos the grass is much bluer than in others, even though it's the same grass.

I'd like to be able to pick a colour or area of the photos, and say 'This should be the same colour', and have the photos adjusted accordingly. Hopefully, then, the colours of the subjects will be more comparable.

Is this possible? Will it work? What Windows or Linux software (preferably not Photoshop, please!) will do it?

Answer 1

Both Lightroom, as well as Photoshop Camera RAW have very simple features that allow you to click on something you know to be white in the image, and based on this assumption, will set the white balance for the image. You would then select this same object in the other photos, which will then correct the balance in the other images to ensure that the object is white. For these tools, there is an eyedropper you use.

This is also available in Photoshop Elements, and Paintshop Photo Pro for a bit cheaper price. Also, consider the free Paint.net, for Windows, which has lots of plug ins that can do this as well. If you prefer open-source, then you should download GIMP, which works for both Windows or Linux. However, GIMP is not quite as simple, though if you are using RAW, the UFRAW tool does have a one step eyedropper similar to Photoshop. Otherwise, it can be much more involved. Google "GIMP White Balance" for your choice of tutorial.

[Do yourself a favor and just get Lightroom, you will be glad you did]

Answer 2

If your photos were taken under different lighting conditions, it is unlikely you will be able to fully normalize all of them relative to each other. Lighting is a very critical aspect of photography, and changing it will indeed change the color balance of your photos. You may have some leeway to correct and improve similarity, however it is doubtful that you would be able to achieve total normalization for all tones and colors in each image.

You can use a tool like Lightroom to automatically color balance based on a particular "neutral" pixel. If there is a particular element in each photo that should be a neutral color (preferably white, but grays also do), you can use the White Balance Picker tool to simply select the same area in each photograph, and correct white balance around that pixel. You might get a closer normalization, but it won't get you all the way there. You could then use the color temperature and tint sliders to fine tune each image.

Answer 3

I don't know of a fully automatic way to do what you want. The closest thing I can think of is the white balance tool. Any decent post app should have an eyedropper that you can click, which lets you choose a point in the photo which is white or neutral gray. From there, I'd try to eyeball the saturation and levels to get the tones matching.

Aperture lets you display photos side-by-side, which is helpful for this.

This obviously doesn't scale past a few shots. Sorry I don't have a better answer for you.