Next we need the source image for the new colour. Colour matching can be done on any selected area of an image or a layer within an image, and the source of the new colour can be another layer within the same image, or a layer in a completely different image. In this case I'm using a selected area in a photo of an orange. To select the source area I've used the Colour Range selection function again.
I've clicked on the top bar of the apple image to make it the active image. Now it's time to open the Match Colour dialogue. This is found in the Image menu under Adjustments.
Most of the settings in this dialogue can remain at their default positions. Make sure that the "Ignore selection when applying adjustment" box is unchecked, and that the Luminance and Colour Intensity sliders are at their middle positions (100).
At the bottom of the dialogue panel, clicking on the Source window will open a drop-down menu showing all the open images, in this case just the two images we're using. Selecting the picture of the orange, with it's selected area, will activate the two other check-box options, "Use selection in source to calculate colours" and "Use selection in target to calculate adjustment". Make sure both of these are checked. Click OK to perform the colour adjustment.
Now all that remains is to clear the selection marquee, using either the Deselect option in the Select menu, or by using the keyboard shortcut Ctrl + D.
And there we are, we've proved that you can indeed compare apples and oranges when they're the same colour, and possibly given some genetic engineers a truly horrible idea.