Tuesday Tips & Tricks: … and We Share Our Work Online

So you went out, sketched, and your sketch turned out rather nice. You want to share it with your friends on USk Chicago group and on your blog and on ….

You took a picture of your sketch or perhaps you scanned it, and it looks like this - flat and grayed out and, for heaven's sake, crooked.

What can you do? You don't have Photoshop, you are just a regular sketcher and cannot pay prices equal to GDP of a small country for a piece of photo editing software.

The answer is  GIMP! GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo editing, image composition and image authoring. It works on many operating systems, in many languages. You can download it here - http://www.gimp.org/downloads/.

The urban legend has it that a few former Adobe cowboys/engineers with a grudge of some sort got together and produced this "almost Photoshop" amazing piece of software and put it up for everyone to use. I don't know if this is true, I read it on the Internet :). But one thing is true - GIMP is FREE under Creative Commons License.

Anyway, download your free GIMP and install it. Now you are ready for action.

Here are steps we are going to take:

1. Rotate
2. Crop
3. Curves to restore contrast
4. Unsharp Mask to sharpen details
5. Scale to reduce size
6. Export to save the file

Let's do it step by step. Open GIMP on your computer and open your unprocessed sketch in GIMP. Let me know if you need help with that and I will add a Step 0 to this tutorial.

Step 1 - Rotate

Click the Rotate button in the Tool Box on the left panel and you will see a grid come up over the sketch and a Rotate window open.

Grab the corner of the image with your cursor and rotate. When the level will look satisfactory release the cursor and click Rotate button in the Rotate window. The rotated image will look like this:

Step 2 - Crop

Click Rectangular Select button and drag your cursor over the sketch creating a rectangle. Manipulate the selection in such way that it is nice and tight around your meaningful image.

When satisfied with your selection, click on Image menu and then on Crop to Selection.

Your sketch will look like this. Nice!

Step 3 - Curves

Photographing or scanning an image grays out colors and and reduces contrast. We will restore that using Curves. Click on Colors menu and then click Curves.

A Curves work window will come up. The diagonal line in this window determines your values and contrasts. Play with it by dragging it with your cursor to see what happens to the sketch due to your action. When tired of playing, get back to work :)! Drag the line into a shallow S curve and nudge its curves up and down a little until contrasts and colors in your GIMP image resemble your sketch on paper in real life. Click OK when satisfied.

Step 4 - Unsharp Mask

Photographing or scanning an image not only grays out your colors and flattens values, it also reduces sharpness. We will restore it in this step. Click on Filters menu, then select Enhance, then Unsharp Mask. You could also work with Sharpen at this level, but Unsharp Mask is smoother and produces less digital noise.

A work window will come up. Drag the levels so some meaningful portion of sketch is shown in the Preview window. Set Radius to 5.0 and Amount to 0.50. Threshold can be 0 or 1, I cannot see any difference between them. These settings will give you a nicely sharpened image and will not introduce too much aberrations. Click OK when done.

Step 5 - Scale Image

Many images coming from cameras or scanners are big, or sometimes you hear them referred to as fat. They have a lot of megabytes in them and can slow down loading pages. It makes sense to slim them down by reducing resolution and size. Click Image menu and then Scale Image.

A work window will come up. If you are preparing the image for displaying it online a resolution of 72 dpi is good, and size should not be bigger than a laptop screen. 

My images for the web usually are about 10x8" and 72 dpi. This is what we are going to do here. Click Scale when done.

Step 6 - Export

We have a very nicely processed sketch now. Time to save it. Unfortunately, some terms in GIMP are not as intuitive as we might wish, and clicking on Save will not produce a file type we want. Instead click on File menu and then select Export. This will allow to save the file in your computer directory in a JPEG format (or many other formats if you want them). But JPEG will do nicely :).

And here's our result - ready to share!

We hope this is helpful, and we will be seeing many shared sketches on USk Chicago group from now on.