Invert image colors and level adjustment - how to

Software RawTherapee
1

Hi

I’ve been using RawTherapee as a editor of images taken with my Panasonic m43’s cameras for a little while, however I’ve come from decades and many versions of Photoshop and find some (ok, most) of the pathways to achieve things in RawTherapee confusing and obscure.

I guess that my first question here is: how can I adjust levels (may also be thought of as black and white points) individually for each of the colour channels?

Next, how can I invert the image colours (to make it a negative).

Thanks

2

Hi, I don’t know for your first question as I don’t feel the to do that.
For the second question, under Film Simulation you should be able to find a nagative HaldCLUT to achieve this result.

3

thanks

I’ve looked and found that, but it seems a bit like either it does nothing or won’t work on 16 bit TIFF.

This is the sort of thing I’m doing:

to date Photoshop has been an excellent solution for me but now I wonder if I need to have two solutions (one for RAW files that are more modern than my ACR is) or to move to DNG

Some of the things that I have discovered in RawTherapee are quite nice but the approach to it is steep.

4

I think you can use RGB curves to achieve selective channel adjustment and inversion:

2036×1414 1.04 MB

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6

@pellicle,I d’ont know what’s was wrong, but I can apply a negative HaldCLUT to a 16-bit TIFF, you can check here: http://filebin.net/dhsl56hn43 (original TIFF + negative from Film Simulation).

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7

Please check the documentation first before asking for help. There is an article which addresses just that.
http://rawpedia.rawtherapee.com/

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8

Hi

thanks for that, cunning thought. I’ve given it a go and wasn’t able to achieve moving the bottom spot.

I’m coming to the conclusion that I’m really trying to get RawTherapee to do things that is probably outside its design parameters.

So I’ll continue using it for some things but it looks like Photoshop stays on my “essential software” list.

Thanks everyone for their replies

9

@pellicle In this case, why don’t you give PhotoFlow a try? It has a workflow based on adjustment layers that is much more similar to Photoshop, and it can do channel inversion with RGB curves plus a lot of more RGB-based editing stuff. There is a sub-category in the “Software” category on this site for discussing things and asking questions.

For the RawTherapee guys: sorry for this little incursion… :wink:

10

What do you mean by that?

11

Hi

there are two “spots” on the line by default. One is the top rhs @ 255-255 end the other is the bottom left @ 0-0 end. I was able to drag the 255 one over to the zero but not the 0 over to the 255 end (which is what I thought the suggestion was to do to reverse the graph slope). I tried bottom first but that didn’t work for me either.

12

Try dragging the bottom left point straight up all the way, and the top right point all the way down.

13

that’s the ticket :slight_smile:
thanks

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