Tips for preparing images for upload:

1. The maximum image size allowed is about 360 px x 275 px. I believe it goes by total number of pixels.
2. The recommend ideal letter height is around 100 px.
3. Try to make sure that each letter is separated and not touching.

The service will accept most common image file formats like GIF, JPEG, TIFF or BMP.

This free service is dead-on. If you have a good quality image that has been prepared well, it rarely misses. This is an invaluable tool that I use all the time. Here are a few tips that I have figured out from my own experience using Photoshop to prepare the images to be uploaded:

1. Try to use black letters over a white background. If you are working from a color image you can convert it to grayscale first, then use the Photoshop Levels adjustment or brightness and Contrast adjustment to make the letters black.
2. If you are working from a low resolution image sample that is not accurate enough for a good sample, sometimes it is possible to upsample the image to 150 ppi or 300 ppi.
3. As an alternative to upsampling, you can sometimes use the Magic Wand to either select the letters or select the background – then invert the selection – whichever gives you a better selection of the letters. Make sure the “Anti-aliased” checkbox is selected in the Magic Wand Tools options. Then you can copy the selection to a new layer or a new file, then click Select > Transform Selection. Hold down the Shift key while dragging one of the corner selection handles and enlarge the selection area to a decent size. Then click Edit > Fill and choose Black as the fill color. This is one way to get a little more detail for the letters.

I can’t tell you how many times this service comes in handy. Many times I will get a job that requires small changes to some website graphics. Most of the website owners don’t have access to any of the source files that could be used to identify any of the fonts and have no clue what the fonts are. With this free service I can ID the fonts in short order.