Line Drawings

[CharlesG]

Good day fine people of Affinity forum.

As always, thank you for your help over the past year, I think you have solved every problem I have posed here thus far.

My question today is about turning black to white.  I am often doing still life photography against a black backdrop.  I would also like to be able to turn all the black in the image to white because I am trying to turn these into line drawings.  I am sure there must be a simple way to do this but can't quite figure it out.

Selecting the subject isn't doing what I want because I am happy for all of the black in the subject to go white in this scenario as well.  Please see my example of a cob of corn. 

The ultimate goal here is to turn this into a black and white line drawing.  Perhaps this isn't the best way to go about this, any help with the question at hand or alternate strategies greatly appreciated.

Thank you!

[v_kyr]

One of several different possible ways would be via "Layer -> New Adjustment Layer -> Selective Color...", aka ...

[thomaso]

13 minutes ago, CharlesG said:

Selecting the subject isn't doing what I want because I am happy for all of the black in the subject to go white in this scenario as well. 

You can define or refine the background pixel selection and thus include or exclude the blacks in the object when selecting the black of the background.

Nevertheless, here an option without any a pixel selection but two adjustments only, one to reduce the background, the other to reduce the colours/hue. I am not sure what you mean by "all of the black in the subject to go white", but you have control over the shades of grey within in the Black & White adjustment and also by switching the order of the two adjustments.

[v_kyr]

For a selection way, you can sample the black background color in the image and then use "Select -> Select Sampled Color..." at around 12-15% which should give you a fine selection of all blacks. Refine/smooth that if needed, then delete all blacks and place a white fill layer or white rect behind (on bottom of the layers panel), or just fill the selection with white instead ... etc.

[CharlesG]

Thank you, these suggestions are doing exactly as I hoped.  But I am having trouble taking the next step into turning it into a nice, simple line drawing.  Does anyone have an idea as to how this might be achieved?  The attached photo was done by duplicating the image layer and changing the blend mode to colour dodge, and then adding a gaussian blur to that.  I came upon this method from our good friends Affinity Revolution.  But this is not quite there for me, I'm hoping for mostly outline and less of the shading.

[v_kyr]

Try out this macro too ...

 

[v_kyr]

If you mean with outline like that here ...

 

... or variations of that, then go to ...

• https://elektrobild.org/photo-filter/outline

[firstdefence]

A simple Live Filter Gradient Map gives a nice fine art pencil sketch, complete with pencil shading.

The centre node can be more or less grey and moved up or down to affect the shading of the corn, all of this is subjective interpretation.

[PaulEC]

For a stronger pencil drawing effect you could try using FotoSketcher (free) https://fotosketcher.com/ after making the B&W image, as above. (You could also add a texture, if you like.)

 

[CharlesG]

I think the gradient map it what will be best for me, it's getting closer, just need to play with the proper adjustments I think.  Thanks everyone!

 

[thomaso]

In case you want to achieve 1 color only (e.g. black or 1 gray) the filter "Detect Edges" + an adjustment to influence the grays may be worth a trial. Below two examples without any pixel selection. Especially in the dark version the leave edges demonstrate by the squared artefacts that a better result may require to remove the black background (via a pixel selection) before this destructive filter gets applied.

[Old Bruce]

I have always been a fan of Highpass then Threshold.

[CharlesG]

Hi Old Bruce, this is very cool and something I haven't tried.  Would you mind spelling out the steps for me?

[Old Bruce]

Mess about with the blend mode (soft light, Overlay) for more fun with the Copy of the original just below.