: Copy/paste to same doc in Photoshop changes colours This is really throwing me for a loop. For some reason, when I copy and paste a portion of an image in a document (with an embedded colour

@Nimeshi706

I think this all comes from the fact that your image is semi-transparent and a confusion of how selections work...

You're first copy/pasting a semi-transparent image. Overlaying a semi-transparent image on itself will inevitably make the image darker. That's just how transparency works; overlay two semi-transparent solid rectangles and you'll see the intersection is darker.

You're then making a selection from a semi-transparent image, but your selection isn't an opaque rectangle; it is also semi-transparent. Using that selection on another layer will only affect that layer as much as is selected. So if you make an 80% opaque selection, that will only delete (or whatever else) 80% of the layer you are using it on. If the layer you are using it on is also 80% opaque, then it will only affect 80% of that 80%, not 100%...

As an example, take these two 80% opaque squares:



Note, they were drawn at 80% opacity; so the pixels themselves are 80% opaque, the layers themselves are at 100% opacity.

We cmd+click the top layer to make a selection, then use that selection to delete pixels from the lower layer. Only 80% of the transparency of that layer is deleted:



So even after deleting the from the lower layer with the selection made from the top layer, there is still the darker intersection:



I'm not entirely sure what the desired outcome is here, but if you want a fully opaque selection from a semi-transparent layer then you're better off using the regular selection tools rather than making the selection from the layer itself.

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@Kristi927

Semi-transparent objects react different on each color backgrounds.
Try putting colored rectangle that matches background underneath the copied semi-transparent one.

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