basicnumerics.com Blog

Last summer, my daughter got a job at CafePress, a company that enables you to make custom tee shirts and other items, and sell them online. There are literally thousands and thousands of designs people have come up with. It is fascinating to scroll through all of the offerings. Whatever your political, religious or philosophical bend, there is a tee shirt for you. Need a humorous saying? They have them, by the truck load. Need a pithy commentary on the cruelty of life? It’s there. Just about anything you can imagine is there.

With this huge assortment, I figured there would be tons of interesting equation tee shirts available. There are, if you are a fan of Maxwell’s equations. You can find many variations of this classic:

but there wasn’t much else. I didn’t see any fluid dynamics or CFD offerings, so I decided to create my own. So far I have made five of them. Here are the images:

I have created an “online store” to house these offerings. You can reach it at www.cafepress.com/basicnumerics. Once you upload an image, you can put it on a wide variety of products. I can chose several styles of shirt (both men and women), a coffee mug and a couple of bags.

Making Equations

When I decided to make the shirts, I figured it would take 30 minutes. I would fire up Microsoft Word, create an equation with Equation Editor, put a cute saying under it, color it, save it as an image and upload it. It didn’t work out that way. I hit snags at every step. First, I couldn’t resize the equations to the appropriate size without Word running out of memory. I am still puzzled by this, but I was able to repeat it several times. The continuity equation would display fine with a 12 point font, but when I scaled it up to 72 point, Word would start displaying out of memory errors and lock up. Additionally, I couldn’t color the equations using Word’s Equation Editor.

It is possible that the more feature rich MathType would work better, but I didn’t have access to that. Instead, I downloaded OpenOffice v2.3 and used the Math module to create my equations. There were no memory problems, but I still couldn’t colorize the equations. Instead, I used Paintshop Pro for this. CafePress recommends that tee shirt images be 2000 by 2000 pixels, with a resolution of 200 dpi. The math module has no way to export a graphic image, so I made the equations quite large on the screen and did a “PrintScreen” to copy the image to the clipboard. On a large monitor, you can get a 1900 pixel wide image this way. I then used Paintshop Pro for the rest.

Recipe

Here is the recipe I used to prepare the images:

• Make the equation in Open Office Math using 24 pt font.
• Open equation on a monitor with at least 1900 pixels of width. Use the magnifier in Open Office to blow it up to full screen. Hit PrintScreen
• Open Paintshop Pro and create a 2000×2000 image at 200 dpi, with transparent background.
• Paste the equation in as a New Image, crop it, copy it and paste as a Layer into the 2000×2000 image
• Use the Background Eraser tool to remove the white background around the equation
• Use the Color Replacer tool to replace the black in the equations with blue at an RBG value of (32, 72, 254)
• Create a vector layer and use Text tool to create a saying to accompany the equations. Set it to a font of 72, 108 or more (whatever fits). Use the font Freestyle Script. (This is set while the text is selected in the text window.)
• Set text to the same color. (Set background color to the same RGB of 32, 72, 254).
• Place the phrase about halfway in window and the equation about ¼ of the way down.
  
• Save file as a pspimage file (native Paintshop format) and as a png file.
• Upload the png file to CafePress.

The recipe is a bit convoluted, and I am sure there are more efficient ways, but it does work.

Creating the Shirts

Once the images are uploaded to CafePress, its easy to put them on products. You simply click on the items you want and add them to your “store”. I chose a variety of shirts, a mug and a couple of bags. Check them out at www.cafepress.com/basicnumerics.

This entry was posted on Wednesday, March 26th, 2008 at 9:08 pm and is filed under Miscellaneous. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.