Remove violet discoloration (partial)?

Stefan Hoffmeister

• 2015年10月16日 10:00

I have a number of photos that exhibit very specific discoloration - sometimes it is a whole area, sometimes it is lens flare which is coloured violet. I would like to learn how to efficiently remove this problem using post-processing (in C1).

One example of what I am talking about can be found at http://imgur.com/j1m1REq

Basically that violet tint on the right side should just ... disappear. Apparently this tinting is a result of lens and sensor not being in perfect agreement on which parts of the light spectrum to filter. In this case, the sensor (stack) is expected to filter more (anything below 405nm of wave length), which it does not do.

I have other cases where lens flare, instead of being bright white, has strong violet discolouration.

Suggestions on how to remove this are greatly appreciated 😊

0

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  Ian Wilson

  Moderator

  • 2015年10月16日 11:15

  

  You could try using the advanced tab in the Colour Editor tool (on the Colour tab).
  
  Use the colour picker to click on the violet colour and try desaturating it. You can use the advanced colour editor (but not the basic one) in a local adjustment, which might be a good approach, to avoid affecting colours in other parts of the image. So you would-
  
  1. Go to the local adjustments tab, and click the + for a new adjustment layer. (You could leave it called Layer 1, or you could change its name to something meaningful like "remove violet on right".)
  
  2. Go down the tab to the Colour Editor tool, select advanced, then the colour picker. Click the picker on a convenient part of the violet patch.
  
  3. Reduce the saturation slider in the Colour Editor tool. (You won't see a change yet.)
  
  4. Use a brush (B for brush, or click the brush icon in the toolbar) and brush over the parts you'd like to remove the violet from. You may want to right click and adjust the size, hardness and opacity of the brush to suit your needs.) You should see the colour being removed.
  
  A good thing about doing it this way is that you get a fair amount of control. You can erase parts of the mask you have painted if you make a mistake (E for eraser, or click and hold the toolbar button to select erase instead). You can also adjust how much of a slice in the Colour Editor is affected, by dragging the white blobs around in the colour wheel, or by using the smoothness slider. And it's non-destructive. You can turn the layer on and off and you can get rid of it again if you don't like the result.
  
  Ian

  0

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