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Xubuntu Articolo 5
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This month, we will focus on sizes. GIMP can use several types of measurements for images. Create a new image by clicking File > New and let's examine some of tahe measurement types. If you can't see the X and Y resolution section, click the Advanced Options text below the Image Size and orientation. Beside Image Size, you see width and height values. To the right of the height value you see a drop-down menu. In my case it is showing 'pixels'. Put simply, pixels are the small dots that make up your display. So in this case the image would be 640 pixels (or 'display dots') wide. Click the drop-down menu to see the other available options. Now, try clicking on inches. See the values change? It is now only 8.889 wide. Why? Because we are now in inches. 8.889 inches wide is the same as 640 pixels wide. Why have these different measurements? If you were working on a banner which was to be used on a web site, for example, then you would need to create your image in pixels, say 400 wide by 50 high. But for print work, your image may need to be 8 inches wide by 12 inches high. Switch between measurement types as needed. Just below the Advanced Options text is the X and Y resolution. This is, by default, set at 72 pixels per inch, also known as dots per inch (DPI), and is sufficient for most computer display and web work. Think of DPI as being detail. The more dots per inch, the more detail you can put in the image. Be aware, however, that a high DPI can slow some PCs down and will result in much larger file sizes. For print work it should be set to about 300, but check with whoever is printing the image beforehand. If in doubt, use 300 DPI. So, with our new image (below), let's move on to rulers. You'll notice that, at the top and the left side of the new image, there are rulers displaying the current measurement type, inches in my case. This allows for precise measuring and placement of items within the image. If I need a circle to start one inch down the page and one inch from the left, imagine how much trial and error it would take to get it absolutely right. It'd be almost impossible! But with rulers, we can be much more precise. Click on the top (horizontal) ruler and drag down onto the image. You'll see a horizontal line (or ruler) appear on your image (above). This ruler does not damage your image in any way, it is merely a guideline and can be moved by clicking and dragging on it with the movement tool. Drag it back to where it came from to remove it completely. You'll notice in the information line below the image tells you exactly where the ruler is on the page (vertically in this case). Drag from the left (vertical) ruler on to the page to get another ruler one inch from the left (below). Where those two rulers converge is where you would start dragging your circle out from (inset). I trust GIMP, I really do. But let's play Devil's Advocate and double check, using a different tool, to make sure there really is one inch between the ruler on the page and the edge of the image. For this, we need the Measurement Tool (below left). This tool is like a tape measure. You click to create a start point, and click to create an end point (below). Between the two points, a red line is drawn. In the information bar (again, below the image) you'll see some numbers. These represent the length of the line, the angle of the line, the width of the line (from start point to end point) and the width of the line (again from start to end). And from my measurement line I can see that the ruler is indeed one inch out. Good job GIMP! Clicking any other tool will remove the measuring tape from the screen. One last tool to cover in this section is the crop tool (left), which comes in handy for keeping a single, rectangular, piece of an image. Select the crop tool, then click and drag a box around the area you wish to keep (below). This area can be moved by clicking and dragging inside the box, or resized by clicking and dragging on one of the inside edges of the box. Notice how the area outside the box darkens to focus your attention inside the box. Use the crop tool to remove uninteresting areas around photographs. Click inside the box area to crop the image. See how cropping the image has forced you, the viewer, to focus on the patio step. Previously, you may have been focusing on the paving stones. If something is unnecessary in a photo, crop it out. Next month we'll focus on some of the more advanced tools used in touching up photographs.
Ronnie Tucker is Editor of Full Circle magazine, a proud Kubuntu user, and part-time artist whose gallery of work can be seen at www.RonnieTucker.co.uk.
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