(Beginner) Photo: portrait in shades of a single color, how to create?

[Amy Choue]

Today I learned from Affinity Photo tutorial about turning a photo into an image that has a look of a pencil sketch. It was good to learn! 

I am wondering how an image like the one below can be created. Could it have been a single image (an actual photo of Napoleon's bust) that have been worked on? Or could it have been a combination of that brown color with an image of Napoleon's bust (which might have been treated with that "sketch filter" effect)? 

To create an image like this, what parts of Photo need to be studied and explored? 

[kaffeeundsalz]

Open a photo and apply a Recolor adjustment to it. Alternatively, place a Fill layer above your photo, set a fill color of your choice and experiment with the Fill layer's blend modes and opacity.

[NapaArtist]

So, I found these instruction for Adobe photoshop to create a pencil sketch, but I don't know why they don't work in Affinity Photo.  Simply, you create layers to Desaturate, Invert in Color Dodge blending mode, apply Gaussian Blur, and the slider can give you anything from a faint sketch to a nice value study.  Plus, another adjustment layer - levels helps strenghthen it.  But I can't get past the Gaussian Blur step with Affinity Photo.  Here is the link to the instructions if you'd like to try it:  https://www.adobe.com/creativecloud/photography/discover/photo-to-pencil-sketch.html .  I've been trying to avoid using P/S, but I've had to keep it on my desktop since there still seem to be things Affinity can't do.

[Alfred]

8 hours ago, NapaArtist said:

Simply, you create layers to Desaturate, Invert in Color Dodge blending mode, apply Gaussian Blur, and the slider can give you anything from a faint sketch to a nice value study.  Plus, another adjustment layer - levels helps strenghthen it.

There are various ways of desaturating an image. Did you apply a Black & White adjustment, or an HSL adjustment with the saturation dialled all the way down, or did you use a different method? Are the adjustment layers nested to the top copy of the image, or grouped with it?

8 hours ago, NapaArtist said:

But I can't get past the Gaussian Blur step with Affinity Photo.

Does that step produce no result, or simply an unexpected result? (I can’t imagine that you’re unable to get past that step in the literal sense of being blocked from doing anything else to the image.)

[NapaArtist]

As I mentioned, I was just following the instructions that worked in Photoshop.  Since Photo has the same filters and adjustments, I had hoped I could also create a sketch with it.  I have no idea why the particular blending modes mentioned actually work. Photoshop has aways been a bit of a black box to me. To desaturate, I chose Black and White in both.  I also chose Invert in both apps.  With the Color Dodge blending mode after the Invert, the image goes entirely white.  In photoshop, the next adjustment, Gaussian Blur brings back a sketch all the way to a value study depending on the slider position, but in Photo, nothing happens.  Gaussian Blur does not bring back the image at all in Photo.  If anyone has a different approach to creating a sketch, I'd like to hear it.  I just need something I can quickly create to trace for my watercolor paintings.

[AffinityJules]

Please note that the desaturated layer needs to be duplicated then placed to the top of the layer stack. The top layer will then need to be inverted again - it will change to all white. That layer is then blurred to create the desired effect.

[AffinityJules]

Look at the history dialogue box, it will show you when the image has been inverted.

[AffinityJules]

And ignoring the Adobe method and instruction - although very similar......

Any undesired effects around the outside of the subject can be removed either by eraser, or by adding a new pixel layer and painting over the areas in white.