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How do you remove the background completely using the color to alpha method ? it looks like it detects the edges well and puts the transparency background boxes in the background, but upon further inspection the new image still has a bit of a background color to it. Wondering how to take the background completely out of the image.

Thanks for the help I hope that is specific enough, Nate

  • Hi. Welcome to GDSE. Can you share the image you are trying to edit? It could be something like a slight gradient or variation in the background. There's probably no way to know for sure without seeing it. – Billy Kerr May 28 at 1:05
  • I don't think that I can upload the image.(at least don't know how) I don't have the link to the download of the image anymore as well. I think you are right though that there is a slight variation of white or gradient in the background. How would I go about removing the gradient/var for future reference ? Or is this too hard to do ? thanks for the help – nateownzz May 28 at 1:32
  • If you have the image file, edit your question and click and drag the image file into the "body" text box, then click "Add picture". Without seeing an image it's hard to tell how much difficulty you will have trying to fix it. – Billy Kerr May 28 at 7:56
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I assume you are removing the background from the photo of a document.

Severa ways to do it:

Blunt way which is usually sufficient:

  • Sample the background color
  • Select the background with the fuzzy selector
  • Select>Shrink by a couple of pixels, and [delete]
  • Select>Grow by at least as many pixels (one or two more pixels is better, to include the edge pixels)
  • Color>Color to alpha

Only small variations of shade in the initial document:

  • Apply color-to-alpha
  • Add a layer mask (Layer>Mask add layer mask and initialize to "Transfer layer's alpha channel". From that point tools apply to the mask....
  • Using the Curves or Levels, make sure that anything below some dark value is completely black. In Levels this is done by dragging the leftmost handle of the Input area to the right, in Curves this means that the curve should have Y=0 for all values beyond some point. While doing this, keep on eye on the edges of the subject, and stop before they appear jagged.

Large variations of shade in the background (photo taken in uncontrolled conditions), and you only need the black and white result:

  • Duplicate the layer
  • Blur the layer heavily (details should disappear, in particular, if this is text, the text should no longer be visible)
  • Set the top layer to "Grain extract". This will gie you a document with an even background, which will be close to 50% grey.
  • You can then proceed with one of the two methods above (after Layer>New from visible)

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