Before you can begin to use some applets or programs, you may have to assemble three SQUARE pictures (images) ... sometimes with the SAME DIMENSIONS IN PIXELS. If any image is not square, you can resize it with Windows 7 Paint or Ultimate Paint.
Windows 7 Paint
Open Paint by clicking the Start button, clicking All Programs, clicking Accessories, and then clicking Paint. Open the selected image file in the usual way. Use Zoom in and Zoom out on the View tab to see a larger or smaller view of the image and to ensure that the desired portion of the image is visable on the screen.
As usual, you can undo any step in what follows by using Ctrl-Z.
Use Cropon the Home tab to crop each image in turn so only the part you wish is visible.
Select Options, then Tool Bar to reveal the tool bar. If significant cropping is required, select the desired square area as closely as possible with the Cut Rectangle tool. Select Image, then Crop. A new file containing the cropped image will open. Determine the pixel dimensions of the new image by selecting Image, then Resize. Subtract the smaller of SizeX and SizeY (the horizontal and vertical pixel dimensions) from the larger and divide by two. Record this result and which dimension (SizeX or SizeY) was larger. Select Image, then Resize Canvas. If SizeX was the larger pixel dimension, set or scroll both of the Left / Right options to the result as a NEGATIVE number. If SizeY was the larger dimension, set or scroll both of the Top / Bottom options instead. Thus if SizeX = 244 and SizeY = 254, set or scroll both the Top / Bottom options to -5. On the other hand, if SizeX = 230 and SizeY = 221 whereby the difference is 9, an odd number, set or scroll one of the Left / Right options to -5 and the other to -4. Click Apply, then save the resulting square image using a convenient name.
If your square images do not have the same pixel dimensions, you can resize them with the program. Find the pixel dimensions of each image by selecting Image, then Resize. Set or scroll the dimensions of each of the larger square images, in turn, to the dimensions of the smallest square image. The program will scale the dimensions proportionately as long as Keep Aspect Ratio is checked. Click Apply, then save the resized square images in turn.