The base image is a Libary of Congress public domain image of a baseball card from circa 1910.
Start cstitch and click the folder icon on the toolbar to open the image. The first step is to choose the colors to use for the pattern. The default mode (visible on the toolbar) is "Num colors to DMC" with a default color count of 80, meaning the program will choose 80 DMC colors for you. (DMC colors are colors that are available as cross stitch thread produced by the DMC company.) The original image has 68,439 colors, but the image was obviously printed with far fewer colors, so we started by trying 20 colors (change the 80 to 20 on the toolbar and click "Choose colors"). The result was too flat, so we went back and tried 30 (if you're not on the first screen anymore, click the icon on the toolbar). Here's the result, which we were satisfied with:
The next step "squares" the 30-color image by overlaying a grid on the image and then making each square in the grid a solid color. The size of the image, the size of the grid squares, and the type of cross stitch fabric you use will determine how large your final product will be. To have the program do the math for you, click on the "Compute dimensions" icon on the toolbar - as you change the square size at the top the final dimensions for your pattern using various fabric types are updated below. We don't know what type of fabric we'll be using yet, but we want the final product to be smaller than a sheet of paper, so based on what the dimension computer is telling us we're going with a square size of 5 (which means the program will lay down a grid line on the image every 5 pixels). The larger the square size, the smaller the final product will be. Click the "Square" button on the toolbar to produce the square image:
If you're following along in the program you'll notice that the color count dropped from 30 to 28! The program chooses just one color for each square, so it looks like 2 colors didn't make the cut (they probably didn't appear enough in the image to get chosen to represent the square(s) they appeared in). There's no way to tell ahead of time how many colors will be dropped, but you can always go back and restart if you're unhappy with the new count.
Some might say the squared image doesn't look very good, and normally we would agree! There are a couple of options at this point. You could go back to the previous stage and make the square size smaller to keep more detail, but then the final size of your pattern would change. Another option would be to go back to the start and rerun the first two stages with more initial colors. If we start with 60 colors instead of 30, we get a square image with 51 colors that looks quite a bit better:
But now we need 51 colors of thread instead of 28, so for the purposes of illustration we'll instead use the square drawing tools to edit the 28-color image above to see if we can make it a bit better. The tools are above the color list and include a tool to draw on the image with the mouse, a tool to fill areas with a given color, a tool to change a color throughout the image, and a "detail" tool - check out the main documentation for more information on exactly what the tools do and how to use them. Another useful function when editing is the "Remove rare colors" function found under the Image menu - use it to replace colors that only appear a few times in the image with similar colors that already appear more often.
The result of editing by hand:
Note that the color count actually fell from 28 to 23 while editing since we removed some "rare" colors that were only used in 5 or fewer squares (you can specify whatever number you like in place of 5). We also removed the name at the bottom of the image and the "B" on the cap since small features like letters don't come out well when squared, and we made the border around the main part of the image one solid color since we like it better that way. Creating a good pattern requires a certain amount of artistry, something that humans are still much better at than computers! You should expect to have to do some editing unless you're willing to use a lot of colors and/or a small square size.
Now click "Pattern" to choose pattern symbols for colors. Colors and their symbols are listed on the right, while the main image is enlarged so that you can read the symbol for each square - to get around you can right click on the image to switch to the square color view, or click/drag your mouse in the preview image in the upper right corner to move the red preview box. If you don't want to change any of the symbols, then just click the "To pdf" button on the toolbar. Enter any title and copyright/licensing you want to appear in the pdf and choose the square size for the symbols in the pdf and then click Ok to save your pattern to a pdf file.
Here are three patterns I get from my image using three different symbol sizes to save: McIntyre_smaller.pdf, McIntyre_default.pdf, and McIntyre_larger.pdf. The program decides automatically whether to print the pattern pages in landscape or portrait mode in order to minimize the number of pages needed - in this case the smaller and larger versions printed in landscape mode, while the default size printed in portrait mode.
At this point it would be a good idea to save the work you've done so that if you decide later that you want to make more edits or save a new pattern size, for example, you won't have to start over from scratch. Click the "save project" button on the toolbar to save your project to a file. What gets saved are all of the images from the four stages, plus any editing history and other settings you might have changed. (Actually, the original image is saved but all that's saved for the other images are the options needed to reproduce them.) Here's the project file for the McIntyre project: McIntyre.xst. If you'd like to take a look, just save the file to your computer and then use the "Open project" button on the toolbar to load it.
For more details try the full program documentation, available from the program under the Help menu or online here. Good luck!