Correct with colour chart and grey wedge

[affi4thg]

Hi,

I'm using an older Mac with 10.13, thus only Affinity Photo v1 (currently 1.10.6) is possible.

I took photos of some paintings , where I placed a colour chart and a grey wedge on the side. Unfortunately the colours and exposition of the photos are not very good, thus I want to correct them with Affinity Photo as good as possible. I do not have a calibrated monitor or other "professional" stuff.

How can I correct colours and exposition using the "calibrated" colour chart and/or a grey wedge in the images as "template"?

Attached is an example of one image.

 

BTW: Is the Windows v2-version running on Linux with Wine? Or is a Linux version planned?

 

Thanks a lot,

kind regards thg

[walt.farrell]

2 hours ago, affi4thg said:

BTW: Is the Windows v2-version running on Linux with Wine? Or is a Linux version planned?

The Windows version is native Windows. No Linux version is planned, according to Serif, but there are users experimenting with getting it running under Wine, e.g.: 

I'll let someone else respond to your color correction question. Welcome to the Serif Affinity forums, by the way

[Dan C]

Hi affi4thg,

With regards to colour accuracy, the only thing you can really do is ensure your white balance is ok by using the white balance tool on your white/grey areas of the card, then using your destination display alongside your colour chart to visually guide your adjustments.

Lee

[affi4thg]

Hi Lee,

thanks a lot for your answer!

So there is no way, to select the black and grey area on the chart within the image (in addition to the white one where it's already possible) with a colour-picker, to say Affinity, that this is 100% black or f.ex. 18% grey? Or for the colours red, green and blue, that should have a defined value on the colour-chart?

Kind regards,

thg

[thomaso]

On 10/23/2023 at 5:36 PM, affi4thg said:

I do not have a calibrated monitor or other "professional" stuff.

How can I correct colours and exposition using the "calibrated" colour chart and/or a grey wedge in the images as "template"?

Your photo lacks in available light (which "merged" in particular the dark areas) and in compression quality (which may influence the colour fidelity). Therefore all colours / the histogram need to be "stretched" and even if you could get the single C, M, Y and K swatches "prefect" it would not necessarily fit for the entire RGB image.

With a monitor of unknown calibration you would rather use the Histogram and Scope panels to check the min/max values + the Info Panel with its various samplers to check specific colours. So you can only try an approximation, for instance …

test farbkarten.afphoto

[affi4thg]

1 hour ago, thomaso said:

Your photo lacks in available light (which "merged" in particular the dark areas) and in compression quality (which may influence the colour fidelity). Therefore all colours / the histogram need to be "stretched" and even if you could get the single C, M, Y and K swatches "prefect" it would not necessarily fit for the entire RGB image.

yes, I had two setups to take the photos, one with two 6000k-lamps directly on the pictures, the other with "inderect" light, because I had to many reflections on the pictures. This are the images with quite bad colours and brightness 😞

I know, lack on equipment, but I'm not a "professional", thus very limited possibilities.

1 hour ago, thomaso said:

With a monitor of unknown calibration you would rather use the Histogram and Scope panels to check the min/max values + the Info Panel with its various samplers to check specific colours. So you can only try an approximation, for instance …

I already tried it with "Auto-Tonwert" and "Auto-Kontrast", the results where not "bad", but I hoped to get it more acurate with the colour-card and grey-scale in the image. I was able to reproduce your settings on the original image, the result is the same as yours und looks much better than the "Auto"-ones.

As far as I understand, I have to approximate the values for every single picture?

Thanks a lot,

kind regards thg

[walt.farrell]

2 hours ago, affi4thg said:

So there is no way, to select the black and grey area on the chart within the image

You can use a Levels Adjustment to control where Black and White are, but not Gray.

https://affinity.help/photo2/en-US.lproj/pages/Adjustments/adjustment_levels.html

And you can get a preview (as mentioned there) by holding Alt (Windows) or Opt (Mac) while dragging the Black and/or White sliders. But you can't actually "pick" a spot and say "make that Black" as you can with White.

[thomaso]

59 minutes ago, affi4thg said:

I was able to reproduce your settings on the original image,

Note, my attached .aphoto file is just an example. There are various ways to get there. Actually every option to influence colour adjusts the contrast but "just" with a different interface (e.g. as "curves", "levels" or "hue, saturation, brightness" etc.)

59 minutes ago, affi4thg said:

I have to approximate the values for every single picture?

I think if all photos were shot with the same conditions than they will work with the same corrections. While objects of quite different sizes and brightness might change the conditions for the camera (light).