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I have an image where a certain region must be 100% transparent. However, another tool reports that not all pixels are completely transparent.

How can I check if a certain pixes is completely transparent or 99% only?

PS. I am creating a nine-patch image and it seems that a shadow is overlapping to the marginal 1px line and I can't figure out where. I cannot add another 1px to height/width, I just need to know how to check transparency level


It seems that color picker tool in Gimp can show alpha values as well, but I cannot find where it shows these alpha values. all I see are x and y coordinates. Look at the image

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up vote 4 down vote accepted

Use the color picker tool. Either

  • check the alpha level on the color wheel (or whatever you use), or
  • Shift-click the image - this will open an information window which shows RGB and alpha values

The information window will stay open even if you click without Shift afterwards. Just close it when you don't need it anymore.

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Great advise. Any such tool in GIMP??? – JoeM May 14 '12 at 15:22
It's the same tool in GIMP. Check the Use Info Window checkbox as well. In the info box, it'll tell you the alpha value for the selected pixel. – MBraedley May 14 '12 at 15:46
@MBraedley I do not see any info on alpha value. I pick the Color Picker tool and hover over the image, but all I get is X and Y coordinates. Look at the images attached in the main message. – JoeM May 15 '12 at 7:42
I found it. In GIMP you have to keep pressed Shift button and then click and Info windows will pop up. – JoeM May 15 '12 at 7:45
@JoeM: Yes. Actually, that should probably be in the answer. I edited it in. – sleske Nov 26 '14 at 14:14

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