Thursday, June 27, 2019

Colouring In With the Aid of a Computer

This Edge Detection example has been done in Krita, whose filter is a bit more sophisticated
than Photoshop's which is basically just on or off.
If you would like to try drawing a landscape (or anything else, really) from a photograph, but your drawing accuracy leaves something to be desired, you can use your computer to quickly create a black & white outline image that you can draw directly over with coloured pencils, chalks, pastels, or paints.

This will let you transfer the outlines of the scene to paper, and then you can go berserk with colours as and how you see fit.

The key to the process is a filter, present in pretty much all image editing programs, such as Photoshop (expensive) or Krita (free) and probably others too that I don't know about.

The filter is called Edge Detect or similar, and it does what it says. It will find the edges of areas within the image and accentuate them extremely, generally reducing everything to a very limited range of tones.

This is the process in Krita (other programs may require some adjustment)

 Find the image that you want to draw. It does not have to be a high-resolution image, as the printed end-product will just be used as a colouring-in guide, but a higher-resolution image will, of course, give you a more detailed end result..

In Krita, you'll find the Edge Detect filter under Filters > Edge Detection.

I've used the Sobel algorithm, with a vertical and horizontal spacing of 2.30

The resulting image is then colour-inverted, which gives you dark outlines and lighter masses for colouring into.

I've then converted the image to greyscale. This is optional, but I think it's a good idea as it means you won't get any inadvertent colour contamination when you add your own colours.

Lastly, I adjusted the Levels to brighten the light areas (Input Levels) and grey out the blacks (Output Levels).

Now you can print this on to an appropriate grade of paper, and set to work filling in the shapes with whatever colours you like. You can use the original image as a colour reference.

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