How to iPaint

Due to a failure of backwards compatibility introduced by Apple in their "Lion" operting system, iPaint no longer works correctly here. All prior operating systems remain usable for iPaint. There are workarounds, but they are not for the faint-hearted.

In 1984 Bill Atkinson, of Apple, created the first interactive bitmap program, called MacPaint for the MacIntosh computer. It sold for \$ 195 and, of course you needed a Mac to run it. For this value (now \$404) you can (almost) buy the entire Mac, and there many tools you can download for free from the web which are equal to or better than MacPaint for the job it was designed for. Of these, I find iPaint the easiest to get started with, and graduate to steeper but higher "mountains" later. iPaint is quite close to MacPaint in spirit and here is some advice for getting started with it.

With MacPaint began the concept of using icons to identify tools. Clicking on the icon opens the tool. And nothing I say here beats experimenting with iPaint itself, since it has only 12 of tools on its palette (toolbar) and few features in its dropdown menus. Even Microsoft’s version of this, called "Paint", already has over 14 tools, but is more garrulous when you click for help.

Since computer software companies preferred to copyright the words they use for common things instead of being content to have their new metaphors become defacto standards, I won’t even try to use "their" terms. For instance, in some MacPaint descendants, the pencil becomes a very thin paintbrush. At any event, the pencil tool changes the color of pixels you drag the cursor over with your mouse, trackpad, or stylus on a tablet. Generically, it is black. MacPaint was for b/w computers, so Apple appropriated the word "palette" (where artists put their paints) for what is now called a toolbar.

Note that you can widen the stroke of the pencil with the slider. This way it also becomes a paintbrush, especially if you change its color.

Actually, the eraser actually reverts the pixels your curser to the background color, generically white. Because you can zoom in (and out) of the picture (use the menu featured labelled View), and thus see the individual pixels, you can be quite accurate in erasing errors. This is perhaps the most important innovation that MacPaint introduced … the ability of editing a picture in a manner that is far easier than pencil, paper and eraser. The word processor revolutionized writing, so the pixel processor has revolutionized drawing.

This or more commonly hidden behind an icon that looks like a rectangle in dashed lines, called a marquee tool. You’ll have to experiment, but it’s obviously related to "cutting and pasting". I use it for moving details, like words, around. If a letter or other feature appear often, it it easier to duplicate a single version far away from the drawing, and drag copies into place. If you font is decifient, you can draw recognizable Greek letters, for example.

This is an unusual tool. I think it gives you a clean (virtual) canvas.

Everybody has their own, undoubtedly patented way of inserting text. Just remember, iPaint sets the pixels corresponding to the message you want to insert. It is equivalent to your having pencilled it all in. Being part of the picture, you can edit each pixel as you would a detail of the drawing.

One of the earliest exercises in a decent course in computer graphics is to ask the student to (re)invent a so-calld fill algorithm. The idea is as follows. Suppose you have three colors: the background (e.g. white), the border (e.g. black) of a region, and the bucket (e.g. red). If you "pour" the bucket of red paint into the region, all of its pixels will turn red. Experiment!

In Euclidean geometry, two points determine the line, ray or segment through the points. Drawing a polygon (succession of segments) the rubberband line tool starts at the first point you click. Then drag a line into a position you want, and let go. Repeat!

I did not find this tool very useful or intuitive. If you know about splines from elsewhere, you can figure out what iPaint is doing. If you don’t, you won’t learn it here. Here is what it seems to do.

The box is for drawing boxes, but you can’t rotate them. The oval is for making circle, but also ellipses. Experiment. The two screens are for setting the background color, and the color of the drawing tools.

Experiment and send me copy for improving this document.

Treat iPaint as an editor of pictures. Import a bitmap file (.png files work well) and mark it up, add to it etc. If the initial file is empty, then you’re drawing on a blank canvas.

13sep09