Defringe photos

17 March 2009
Posted in Photoshop

You see this problem in lots of cameras. I think it is called blue or purple fringing. 

There are a few techniques you can use to defringe a photo.   They are mostly based on selective color and masks.

here's a nice technique

1. Duplicate the background layer (Ctr/Command-J).
2. Go to Filter > Blur > Gaussian Blur and use a value of 180.
3. Click the eye icon next to the duplicate layer in the layers palette to hide it for now.
4. Go to Select > Color Range. Move the cursor over the image window (it turns into an eyedropper) and sample the color in the blue fringe. You may need to zoom in, so just press Ctr/Command-Spacebar to temporarily switch to the zoom tool and drag over the area you want to magnify. It also helps if the eye dropper is set to sample a 3x3 pixel area (You can do this before by selecting the eyedropper in the toolbar and changing the sample size in the options bar at the top, then it will use that size in all the dialogs). Adjust the fuzziness slider to 90 in the Color Range dialog.
5. Go to Select > Modify > Expand selection and enter 3 pixels.
6. Go to Select > Feather > and enter 2 pixels.
7. Click the eye icon next to the duplicate layer to make the layer visible and click the layer in the layers palette to make it active.
8. Change the blending mode to Color (this preserves the underlying detail or luminance values and changes only the color).
9. Click the Add Layer Mask at the bottom of the layers palette (since you have a selection in place, the mask will hide everything except the selection).
10. There will still be some blue fringing, so make sure the layer mask is selected (click on it in the layers palette so that it has a border around it), select the brush tool (press B), press D to set the foreground color to white, set the brush opacity to 100% in the options bar at the top, and paint over the blue fringing to clean up any stray color.

second thing you can do :

1. Go to Select > Color Range. Move the cursor over the image window (it turns into an eyedropper) and sample the color in the blue fringe. You may need to zoom in, so just press Ctr/Command-Spacebar to temporarily switch to the zoom tool and drag over the area you want to magnify. It also helps if the eye dropper is set to sample a 3x3 pixel area (You can do this before by selecting the eyedropper in the toolbar and changing the sample size in the options bar at the top, then it will use that size in all the dialogs). Adjust the fuzziness slider to 90 in the Color Range dialog.
2. Go to Select > Modify > Expand selection and enter 3 pixels.
3. Go to Select > Feather > and enter 2 pixels.
4. Go to Layer > New adjustment layer > Hue/Saturation
5. Reduce Saturation in the adjustments properties