How to remove chroma colors from a photo

[Gerald McClaren]

I was given a photo slide to restore and it has a lot of chroma color under the neck and all around the outer edges of the photo. Can someone please tell how can I remove the chroma colors from this photo.


Gerald Sr.

[peregrina]

If you have a RAW file, you can do that in Lightroom (best option). Otherwise, in Photoshop under Filter>Lens Correction, you can adjust the red/cyan/blue/yellow fringe

[secretagents]

What do you mean by chroma color?

[Gerald McClaren]

Green, red, and blue noise on the photo slide. The color noise are on the face, edges of the photo, and under the neck.
Gerald Sr.

[secretagents]

I can't see any of that noise in that downsampled picture which is interesting, so perhaps you could downsize a copy of your original and then blow it up to its original size again and use that as a layer in color mode on top of your original image.

Or perhaps you could go in Lab mode and slightly blur the a and b channels .

Or use a denoising plugin.

[Gerald McClaren]

If you look closely under his neck there are the chroma noise or color noise. Also, look on his right-hand away from his watch, and on his left-hand edges outer edge of the photo. I'll see if I can download a larger copy. Thanks for your response. I tried removing the chroma noise in lightroom, but that didn't work either.

Gerald Sr.

[peregrina]

I don't know if this image is at the real size; but more than chroma noise, what i see is artifacts due to bad compression settings. if this is the case, I would try using gaussian blur with masks and hi pass filter afterwards.
Better yet, do the above but "by hand"

[Flora]

I agree with peregrina about the compression artefacts, but I can also see how it affects the colours .. (Attachment 1)

Gerald, you are probably working on a higher resolution image, but obviously you still have the problem...

What I used is, maybe, the oldest and less sophisticated way of minimizing this problem:

• Created a new Document of the image.

• Changed the Mode of this newly created Document to L*a*b* (Image>Mode>Lab Color).

• Opened the Channels Tab and used Gaussian Blur on *a and *b leaving the *Lightness Channel untouched.

My result: (Attachment 2)

Shift-Drag the modified L*a*b* background on top of your RGB background and continue with your retouch.

One thing ... this method tends to make all the colours in the image more uniform/flat ... so you might use a Layer Mask to hide the effect on the parts of the image you want to keep 'original'.

Hope this helps.

[Gerald McClaren]

Hi! Flora, when I had scanned these film slides with an Epson Photo Scanner those red, green and blue color noise were on them already. I thought those were chroma noise or color noise. What do you mean compression artifacts? Is it because the slides were from jpegs? I thank you Flora and everyone for their input. I'll try your method Flora and see how it will come out. Thanks again

Gerald Sr.

[andrewrodney]

Originally Posted by peregrina

If you have a RAW file, you can do that in Lightroom (best option). Otherwise, in Photoshop under Filter>Lens Correction, you can adjust the red/cyan/blue/yellow fringe

Or load the TIFF into Adobe Camera Raw and try using the new noise reduction tools in 6.1 there. Yes, it works way, way better on a raw. Just do an Open as Camera Raw and the TIFF will open in ACR.