Wednesday 25 February 2015

Gimp: Using the Paint Brush to Touch Up Oil Pastel Scrimshaw

Those of you who’ve tried it will know oil pastel scrimshaw is fun, messy and somewhat unpredictable. You’ll also know it’s difficult to avoid some kind light glare when photographing the end result, regardless of whether you dull your flash using tissue paper, use overhead lighting rather than a flash, or use natural lighting. It’s just the nature of the pastel.

flash reflection
daylight reflection
flash softened by tissue
Scanning produces a result without the reflection, but limits the size in which you can work. This piece was scanned to avoid reflection distorting the picture.


Once the piece was scanned, I noticed that the colour was uneven and the line-work needed cleaning up—how much depending on how much of the original scrimshaw effect I wanted to preserve.

First, I opened the scan in Gimp and then saved the scan with a different name before I started work. This saves the original picture, and means I can start from scratch if I muck up the modifications.

After that, it was a matter of working out what I wanted.

I noticed the picture was lighter than I wanted, more grey than black, so I used the Bucket Fill Tool to drop a layer of black through the picture. This worked fine, but a second look showed me that there were areas of the picture that the bucket fill had missed. These areas occurred where a shape was fully enclosed from the background, such as in the gum leaves, the dragon’s head, some of Anna’s hair. It looked odd and needed touching up. The question was ‘How’?


While I was looking at the grey-black effect, I noticed I hadn’t trimmed the sketchbook binding from the image. This should have been the second step after saving the image with a new title.


I tried two ways. The first was to use the Free Select Tool (symbolised by a little lariat in the Toolbox) to trace the section I wanted to darken, and then to use the Bucket Fill Tool on the area. This was okay, but not quite what I wanted.

The second method I tried was to use the Rectangle Select Tool to choose an area, and then go to the Zoom Tool (represented by a little magnifying glass in the Toolbox) and zoom into the area until the scrimshaw lines were 1-2 mm thick on the screen.


After that, It was a matter of playing with brush sizes and Opacity in the Paintbrush Tool, Brushes and tool options boxes. I like this setting because it allows me to skim close to the coloured edges without covering them completely, so I can soften an edge rather than erase it completely. I also use a really small brush size. It is important to remember that the smaller the brush size is, the harder the edge it will produce, and the darker the line. For some of the smaller areas, I had to reduce the brush size to about 8.17, but I preferred the 15 to 18 mark for most of the filling work. It was just more forgiving and suited to most of the spaces that needed touching up or filling.

Brush pallet and options box for adjusting.


The dotted circle shows the size of the brush compared to the size of the scrimshaw line being neatened.
Another illustration of brush size - this one is smaller than the last.
There are two effects you can create with this setting: a single flat stroke and stippling.

The flat stroke is simple. You just move the pointer to create the line you want. You need to remember that this setting does not draw to the edges of the circle marking its effect, and that the darkest area will be in the centre. This gives you room for error. It is also important to remember that you can undo any brush stroke using ‘Ctrl’ ‘Z’ BUT that the longer you have drawn without ‘lifting’ the pen (usually by releasing the mouse button), the more will be undone. It is best to do relatively short strokes so that you only undo areas you need to correct, rather than a large stroke of which only the last few millimetres needed undoing.


Stippling is where you use dots (mouse-clicks) to fill an area. The effect isn’t as dense as a line effect, and allows you to leave some of the area you are filling unaffected so that some of the original colour comes through. The edges of the dots allow for a softer outline to be created, although it can take longer to undo a patch of stippling, than to undo a single line.


Gradually work your way through the picture until you have achieved the finish you want.




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