You can use the Levels function to correct almost every "normal" color cast. You can then correct your shadows and highlights with the Curves function described in section 2.5.9.Ĭolorcast.png after the correction of the red color channel By getting rid of a color cast, for example, you could cause your image to become too bright in areas. You can proceed to edit your pictures with other functions in GIMP. Remember: This is initially about the correction of color cast images. In such a case, you should forgo the automatic functions and adjust the color histograms individually. A yellowish color cast will require correction of the red and green channels, at the very least. However, if you come across an image with a color cast created by a secondary color in the RGB color model (such as cyan, magenta, or yellow), you may have to adjust two, or even all three, color channels.
But it is important to choose a really neutral gray area in the image otherwise, it could distort the color levels.
The use of this eyedropper is often sufficient to correct your image. It provides good means of getting rid of a color cast in an image. Its function is to allow you to select a neutral gray as your reference color. You might notice that there is a third, gray eyedropper (tool tip: Pick gray point). This procedure is often sufficient to correct the color levels.Ģ.6 TOUCHUP WORK 1 - REMOvING COLOR CAST W Then proceed to use the white eyedropper (tool tip: Pick white point) on the white area. Select the black eyedropper (tool tip: Pick black point) and click on the black area of the image. If you use this second option, your image must contain true black or white areas. You can click either of these buttons to select a black or white spot, respectively. What next? Simply adjust the color according to your personal preference, and voila! Save the image as colorbalancel.png in your exercise folder, and you're done.Īnother method for correcting images with color cast is by using the black and white eyedroppers in the Levels window. If you check the Preview option in the Levels window, you can immediately view the adjusted image. Doing this will change the mid-tones of the red color channel. You can skip the black triangle for shadows and the white triangle for highlights-I'd say that the automatic correction did a perfect job balancing them.Ĭlick and hold the left mouse button on the gray triangle and drag it to the right. Underneath the histogram are the adjustable triangles that you are already familiar with.
Now you should see the histogram for the red color channel in the Levels window. 2.60 colorcast.png-17.0 [RGB, 1 layer) I'iWvJIiB-rjI^fl ° ^ ^ £ile Edit Select View Image Layer C & JSgtj.Select the red color channel.Ĭolorcast.png after automatic tonality correction has been applied (prior to correcting the red color channel) For some images with a slight color cast, this action may be sufficient.īy clicking the Channel drop-down menu on the top in the Levels window, you can choose the red, green, and blue color channels separately so that you can correct each color individually. The image should be visibly improved, as now the real black and white tones can be seen. Using the Levels dialog that appears, first change the settings of the RGB color channel by clicking the Auto button. You can use the function Levels in the Colors > Levels menu to correct the bright-dark values in the image. The colorcast.png image has a strong red color cast. You will notice that the image has a distinct red color cast, which means that the red color channel values are faulty. Open the image colorcast.png in the SampleImages folder on the book's DVD and save it in your exercise folder.
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