1. A computer-implemented method for combining a digital product image with a digital design image to create a blended digital image indicating the appearance of the product after the digital design image has been printed on the product, the method comprising: creating a modified design image by, for each pixel of at least a portion of the pixels in the design image, (a) modifying the alpha value associated with the pixel and (b) modifying the color of the pixel, and generating a blended digital image by combining the modified design image with the digital image of the product.