ORIGINALLY POSTED BY ALLY FOR THETAZZONE/TAZFORUM HERE
Lets have a look at changing a photograph to lineart. Some photos are going to be easier to convert to lineart than others. For example, the simpliest would be anything with straight, definate lines … like buildings, walls, furniture etc., Some images are going to convert well straight away, others may need a little more manipulation.
You are going to have a couple of different filters that can be used and a couple of adjustments to tweak …… like we would expect anything else from Photoshop
Grab my birdie image below to practise on if you like …. no larger images than this, so just right click and save as.
Once you have the image open in Photoshop, double click on the b/ground and accept the default Layer 0 …. or rename it. Then duplicate the layer and from the top menu bar go to Image>Adjustments>Desaturate or use the keyboard shortcut Ctrl+Shift+U
The Find Edges filter, found under Filter>Stylize>Find Edges doesn’t give us a dialogue box to tweak, but go ahead and use that filter now on the desaturated layer if you like. You can see that it hasn’t done that bad a job, especially with this image.
Go to the top menu bar and use Image>Adjustments>Levels and you can punch in the same numbers that I have below, or use some of your own.
Lets back up and try the Poster Edges Filter. In your History Palette click back on Desaturate. If your history palette isn’t open go to Window>History. Open the Filter Gallery by going to Filter>Filter Gallery and then open the Artistic Folder, then click on Find Edges. I don’t know if you can see the numbers I punched in, but they were Thickness 1 – Intensity 1 – Posterization 6. Click OK.
So that looks awful Go to the top menu bar and choose Image>Adjustments>Levels to bring up the levels dialogue box. You can see in the image below, that I’ve really had to push the numbers to get a reasonable effect. I think the eyes have turned out better in this version than the find edges version.
In the final image below I have blended together the Find Edges and the Poster Edges layers. I filled the b/ground (birdie) with white and used the eraser tool on both of the other layers to take away what I didn’t want. I could have gone in and dodged some of the darker lines to make them less prominent, but overall this hasn’t turned out too bad for a rather complicated image. Try doing a building yourself and you’ll see how much easier it is
You can also use Curves and Brightness/Contrast from the top menu bar instead of Levels. You can also leave the b/ground bird as it was and take the opacity of your desaturated down to bring some colour back in to the bird.