Two Types of Images in Acorn


There are two basic images in Acorn you must be aware of. They are VECTOR images and BITMAP images, also called “RASTER” images, and we have to deal with them differently. Vector images are drawn with the various SHAPE tools as well as the TEXT tool. Rectangles, circles, stars, lines, AND letters from the text tool are all vector images. They are not drawn with the bitmap tools, which is why you must be aware of these differences. If you aren’t aware of them, you will be sorely frustrated. Bitmap images can be altered with bitmap tools. These are tools like the selection tools and the eraser tool, although there are others. Choose the rectangle selection tool, for instance, and you can select a rectangular area, and then you can press the [Delete] key to delete that area. Same goes for the eraser tool. Put the eraser over what part of the bitmap (raster), image you want to get rid of, hold down the mouse button, drag, and voila! It’s gone! But you cannot use these deletion tools on a vector image. That’s because vector images are not made up of little pixels like a bitmap image. The vector image is one solid and very complex group of mathematical formulas, and bitmap tools can’t go there. To see this, picture a checkerboard with all the checkers in their squares on the board. Yank the board out from under the checkers like those magicians who yank out the tablecloth from under a perfectly set table. Now consider the checkers in their perfectly laid out grid. By taking away various checker pieces you can make a crude picture of sorts. You can alter this whole image with a bitmap/raster tool – in this case your fingers! The checkers in a grid is akin to a bitmap or raster image. We can delete pixels, change their color, sharpen them, change how many pixels there are per square inch, etc. Now ignore the checker pieces and consider just the board. The board is akin to a vector image. It’s one board, one chunk, there’s no way to erase pieces without taking a saw to it and wrecking the image, and that’s the difference between the board, (the vector image), and the checkers, (the bitmap/raster image). The eraser and various selection tools cannot be used to alter a vector image. I fell into this dilemma when I first began using Acorn. From using Photoshop Elements I was used to “simplifying” a layer. That converts the vector image to bitmap, where I can freely use my bitmap tools to alter. So when I found that my Acorn bitmap tools couldn’t alter the image, I looked for…drum roll…you guessed it! My experience with PSE had me looking for “’Simplify’ the layer.” But that was their phrase, not Acorn’s. Eventually I found the equivalent phrase in Acorn, and you can too. Go to the Layer menu. It’s at the top border of the Mac screen. The option “Simplify the layer” in this menu is not there because that’s what PSElements calls it. Acorn calls it, “Rasterize Shape Layer.” This finally made sense because “rasterize,” you’ll recall, meansbitmap.” So in the Layer menu, choose the “Rasterize Shape Layer” option. Now go back to that layer and select and delete, erase, etc. Here’s the tipoff: If you can’t alter an image with bitmap tools, make sure the layer that has the image is selected and try again. Still no effect? Go back to Layer in the menu. Is the “Rasterize Shape Layer” option showing as a solid black? Yeah? This means it’s still a vector image and you can click that live option to choose it. Choose “Rastersize Shape Layer” again. Kerblang! You’ve instantly changed the image in the layer to a bitmap/raster image! Now try to alter part of the image with the eraser, just to test. If the eraser works, you’ve successfully converted the shape to a bitmap, or raster image, which means all the bitmap tools will work. That is, you can now mess with the checkers on the board. Be sure to press Command – Z to undo the erase. (The eraser is just an easy way to test it.) Although it’s easy to picture an image made up of tiny pixels or checkers pieces, many don’t realize that the word “raster” means “bitmap,” which is why I’m making such a big hot deal over this term. That’s the word you’ll be looking for in the Layer menu. The words “bimap” or “simplify” is not there. “Rasterize” is there.

It probably sounds like I’m picking on PSElements since I’ve already mentioned it in a previous post and this one. I’m not. I’m just trying to point out that graphic editors do basically the same things, but the controls are different. It’s kind of like working with a Mac and a PC. They do exactly the same things, but their operating systems are quite different and require some practice and new knowledge to make the new computer you might not be so familiar with easier to operate.

Another vector image you’ll be working a lot with is TEXT. You’ll find my hints and revelations for working with TEXT in another post.

Hope this helps!



Thanks for the post!


Nice! It’s pretty useful to know!