Sample colour combined with curves and info palette

[Littletank]

I am very new here and coming from PS I have lots of questions and I hope I am posting them in the correct place. Working in LAB, what I want to do is to select a point on a black & white image, mark that point and have the reading displayed in the info palette. Then, with the curves palette open, move a pointer or a cursor to the previously selected point and for that position to be shown as a marker (a small circle) on the curve corresponding to the L value of that point. This is very easy to do using PS and is part of a work flow in modifying tones in images.

 

I have tried using the Sample colour picker but that appears not to have the facility to mark the selection and I cannot find an adjustment tool that I could select on the Curves adjustment layer palette. Am I missing something or am I trying to do something beyond the capabilities of AF?

[MEB]

Hi Littletank,
Welcome to Affinity Forums

Go to menu View ▸ Studio ▸ Info to open the Info panel. Drag the target icon from one of the samplers in that panel over the image to mark a point in the image. Add a Curves Adjustment (menu Layer ▸ New Adjustment Layer ▸ Curves Adjustment). It should be already displaying as LAB - click the dropdown that says Master on the right and select Lightness. Use the Picker button to click (and drag a little) over the point you have marked on the image (you must drag it a little for it to appear in the curves graph).

[Littletank]

Thank you very much, MEB, for your instructions which, with a slight amendment, I was able to follow and, so far so good. In the info panel there are 2 columns both of which I set to LAB then the target icon was dragged and dropped onto the image and the L value was displayed in the left hand column. What I am now looking for is the right hand column to display the same L value as the left hand column when the picker is dropped on top of the  target and then for the L value in the right hand column to follow the changes when the curves graph is moved whilst the figure in the left hand column does not change. After several attempts I am not able to make this happen it looks as though it is not possible to switch the picker off. I hope this can be sorted out as everything is looking good.

[Littletank]

MEB, I must apologise but what I have been trying to do is not correct. The first part is fine up to the Curves adjustment layer so I am going back to the drawing board and, when I have sorted myself out, I'll be back.

[Littletank]

Working on the belief that pictures speak louder than words the following video demonstrates what is done in PS and I would like to do in AP:-

 

 

Unless you are interested in how the lightness value varies depending on which colour space you are working in my quest starts here which is about about 3 minutes after the start of the video and loading of the info panel. Once the change to the image has been demonstrated the rest I think I can manage. 

[MEB]

Hi Littletank, 

I'm not familiar enough with using the zone system for photo editing and so probably not the most suited person to translate that workflow to Affinity Photo without researching a little. Hopefully James or someone else may be able to give some help. 

[Littletank]

Thanks, MEB for your comment. It is not about the zone system that I need help, but about how to use the tools in Affinity Photo to achieve the same result that Photoshop gives when using the Info Palette, Colour Sample tool and Curves adjustment layer. Using the information which you have already supplied the result is almost there but not quite and it would be good for Affinity Photo and me if the sequence could be completed.