There are several answers to this question. Nowadays, most people think they can pull an image off the web and you can somehow magically make it appear on a shirt. The first concern you need to have is if the image is copy righted or not. After you've made that determination you can then begin to explain that images that are on the World Wide Web are only good for the web. The reason being is that images on the web are more times than not only 72dpi. The lower the number of dpi. the lower is the quality of the image . As a screen printer we know that it is very difficult to draw from an image with low resolution and the detail in the image will suffer tremendously. Secondly, many times a client brings in a jpeg image that has multiple colours in it and they think this is ready supplied art. Please ask your agency for a VECTOR image.