Introduction :

This tutorial covers the creation of a two-tone sketch, isolating highlights and shadows in a 'chalk and charcoal' shading style, using the Sketcher Plugin and PhotoGrey in combination with the standard abilities of your graphics application. The bulk of this tutorial examines each process involved, and at the end there is a visual step-by-step walkthrough.

The Source Material :

The original photograph is a nice source of highlights for this style, contrasted with the dark jacket, and a rather midrange intensity background that will be free of too much noise. The two-tone style is obviously suited to images with a wide dynamic range, although of course image processing can produce contrasting sources from almost any photo. You can copy the above image and paste it into your graphics application if you want to work through the tutorial.

Greyscale with PhotoGrey :

The first step is to get a useful greyscale for use with the Sketcher Plugin. The most reliable method to capture skin tones as pale greys is with an orange filter.

PhotoGrey settings and result

The two-tone shading separates the image into light and dark parts. To capture this, the lights and darks need to be rendered in two separate passes.

Creating Shadows :

From the source image, use you graphics application's colour manipulation functions to isolate the shadows, such as a curve or histogram function. For the sketch, we want to discard all intensities above a midpoint so they aren't drawn. In this case, scale intensity from light to dark over the bottom range of the histogram.

Histogram curve used

Result of Histogram

Now the Sketcher Plugin can be used to shade in the details using the 'NiceSketch.sms' settings.

Result of Sketcher Plugin

Creating Highlights :

For the highlights, the reverse of the shadows is wanted. From the greyscale image produced by PhotoGrey, the intensity wants to scale only the top end of the image intensities.

Histogram curve used

Result of Histogram

The Sketcher Plugin draws areas of darkness, not light. The lights and darks of this image thus need to be reversed, and this is very easily achieved by using a Negative filter

Negative of the highlights

Now the Sketcher Plugin will draw the highlights in pencil strokes.

Result of Sketcher Plugin

To get the light strokes, use the Negative filter on this image again.

Negative of the highlight sketch

Final Composition :

To create the final portrait, the shadows and highlights need to be combined. A base colour is wanted to fill in the mid-range. Create a new image the same size of the source (or just copy the source) and fill it with a mid-intensity colour, picking a hue and saturation to fit the mood you want. Paste the shadow sketch as a layer with Multiply type blending. Finally paste the highlight sketch as a layer on top with Screen type blending.

The final image!

Step by Step Walkthrough :

 

 

 

 

 

 

PhotoGrey Orange filter

 

 

 

 


Duplicate

 

 

 

Apply Histogram change
for shadows

 

Apply Histogram change
for highlights

 

 

 

Sketcher Plugin

 

Negative image

 

 

 

 

Sketcher Plugin

 

 

 

 Create new image of same proportions
Filled with midrange colour

Negative image

 

Paste as layer
with Multiply blending

 

Paste as layer
with Screen blending

 

 

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