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EMG news for February 2008
The Gimp for Beginners: Two Basic Tasksby Valerie Joanne Higgins
If you are an artist in traditional media and you want to sell digital print copies of your work, you will need to scan it for printing, and if selling on the internet you may also need to create a web-size copy for display. While your scanner's editing software might satisfy a casual user, its scaling algorithms and color level adjustment are not usually as good as those used in specialist editing software such as The GIMP. While you might not have an interest in creating digital art, you certainly want to display your work to its best advantage without paying out for expensive software. The GIMP is both free of cost and open source, and ideal for this task.
If you are just starting out as a digital artist you might be finding that a mouse is a clumsy thing to draw with. If you haven't yet committed yourself far enough to this digital experiment to want to buy a computer drawing tablet, can't afford one, or don't like them, you can always transfer your hand-drawn sketches into The GIMP for digital coloring. You can lift just the outline of your drawing onto a separate layer so that you can happily color behind it without fear of smudging your line work.
You can find The GIMP at http://www.gimp.org.
Adjusting Color Levels and Scaling
We'll now learn how to adjust color levels, and scale our images down to a web-appropriate size. First, find your scan on your computer and "Open With" The GIMP.
Here is my little pastel rat drawing looking a little drab. I need to increase his colour range so that he looks as clear and bright as the original. Right click inside the image, go down the menu to "Layers", across and down to "Colors", then across and down to click on "Levels".
This will open a dialogue box like this:
Look at the controls I have circled in red. There is an "Auto" button and three color pickers. Usually you will find that all you need to do is click on the "Auto" button and The GIMP will stretch your range of colors for you. If you are happy with that result, just click OK and then "Save As" your image with a new name. (It's a good idea to keep an unaltered copy of the original scan and also an .xcf copy with your edits.) Otherwise you can hit cancel and use a color picker to define where on the range your blacks, whites or mid greys should be. To tell The Gimp which shade should show as black, click on the left of the colour pickers, then go to your image, find the pixels on your image that should be black, click on the image at that point, OK the colour selection, then hit OK on the "Adjust Colour Levels" dialogue box. If you would prefer to define white, go through the same steps but first choosing the colour picker on the furthest right. You can use the center color picker to define mid grey, but this works best on grey scale images and can have wildly weird effects on colour images.
Here is my pastel rat with his colours brightened:
Transferring a hand-drawn sketch into The GIMP to color on the computer
First of all you need a scan of your line drawing:
If you want to keep the original sketch, you can get away with a pencil drawing, but you will find transferring a sketch to computer easier if you ink your sketch to give it more contrast.
So I've scanned my sketch and opened it with The GIMP.
Er, OK, my scan is the wrong way round, I might find it easier to see what I'm doing if I rotate the image. Click inside the image, then go to "Image", then "Transform" then "Rotate 90 degrees CW" (or whichever rotation you need), like this:
You could also use the menu you see across the top of the image window to do these tasks, but when you are used to it, I think it is much easier and faster to just right click into the menu. If you find an easier way for you to do some things than the way I recommend, then use your way. The GIMP is a very flexible program and there are often several ways to achieve the same result. The right method is the one that suits you best.
Now you want your sketch to have as clear and sharp contrast as you can get, to make it easier to separate your line drawing from the background. So right click then go "Layer" then "Colors" and click on "Brightness-Contrast" . That will give you this little slider box:
Play with the sliders until your drawing is as clear and distinct from the background as you can get it. Then hit OK.
Now go to the tool palette in "The GIMP" window. About the fifth tool along you will see an icon of a finger pointing at three coloured squares. This is the select by colour tool. Click on it and go back to your image.
The next bit will be easier if you zoom in on your image, Right click, go "View" then "Zoom" then choose your percentage. 200% would be good.
Carefully click on the line of your drawing. You will see the selection you have made outlined by vibrating dashes (they are showing as tiny white dashes on this screen shot, on your screen they will be animated). We call these "marching ants."
Scroll around your screen and zoom in and out to check that you have all your line drawing selected, and nothing selected that you don't want.
If the color of your line varies slightly it might not have all been selected. If this happens, then with your cursor inside the image, hold down the shift key on your keyboard so that a + (plus) symbol appears next to your cursor. This allows you to add to your selection without replacing it. Continue holding down Shift until you have clicked on and selected all of your lines.
At this stage, if you are working from a pencil sketch and the paper was perhaps a bit textured, you may find you have selected some bits you don't want -- speckles in the paper, or a bit of scanner burn. Choose the tool in The GIMP window that looks like a lasso. Take the cursor to your image and hold down the control key so that you see a – (minus) symbol next to your cursor. While holding down the control key use the lasso tool to draw a loop around any bits of the selection you want to remove. This will allow you to remove the bits you don't want from the selection without losing the parts of the selection you do want.
You have your selection? Good! Now right click in your image and go "Edit" then "Copy."
Go to "The GIMP" main toolbox menu and open a new image the size you want your finished image to be. Create a new transparent layer in the new image. (using the "Layers, Channels, Paths" dialogue box as I showed you last month)
Right click "Edit" then "Paste" your selection on to the transparent layer. Position it with the "Move layers and selections" tool, (the one that looks like a four pointed cross). Your selection will be quite slender being only a line so you will have to position the tool quite precisely. Zooming in and out will help.
When your drawing is in the correct position, go to the "Layers, Channels, Paths" dialogue box and click on the anchor symbol to anchor down the "floating layer." (If you ever find yourself working with The GIMP and your tool, pencil, paintbrush whatever won't make a mark, double check that you don't have an active selection, anchor any "floating selections" and/or right click and go "Select" then "None" and, hey presto, it should work again.)
Save your new image as an .xcf file (with a different name). "Save As" your old image as an .xcf with a different name to the original scan so that you have both versions of those files to refer back to if needed. Close the old image.
Now go to the "Layers, Channels, Paths" dialogue box, select the background layer and create some new transparent layers under your sketch layer (its the extreme left hand sheet of paper icon on the same row as the anchor)
Now you can color behind your sketch drawing without any risk of damaging your line drawing.
So give it a go and have fun!
Oh, just one more stray tip
The "Tool Options" dialogue box allows you to adjust your current tool, e.g. you can adjust the transparency of your brush, decide whether to "dodge" or "burn", or choose whether to make a crisp selection or a feathered one. You might find "Tool Options" docked to your "The Gimp" palette window or it may be floating round as a separate window of its own. If you can't find it, right click inside your image and go "Dialoges" then "Tool Options" and it will come to the front of your screen.
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