On occasion, a client supplies a final Illustrator file only, with no image. If this is the case and that file is all the client can provide, you'll have to open the file in Photoshop and rasterize it.
Note: Rasterizing a file basically changes the file to a set resolution and size. If you attempt to resize the image after it has been rasterized, you will be limited by the original rasterized image size; whereas in Illustrator, a file can be scaled to any size without any detrimental effects.
Regardless of what elements the image is made up of, it will have to brought into Photoshop to be adjusted. The only time the image or file may not have to be adjusted is if the person preparing the Illustrator file has prepared the file properly for packaging, which is very rare.
When you open an Illustrator EPS file in Photoshop, a dialog box, shown in the figure, opens, asking you for a size and resolution of the file before it begins to rasterize. Check your specifications to make sure that you rasterize it to the correct size and resolution.
We want to open the file in Photoshop because we have to make some color adjustments to the image before it can be used as a packaging image.
Just about every Illustrator file I have seen has been produced by a creative person who has no concept of, or who may not even care, how the final file will be printed. As long as her client is happy with the final image, her job is done. The problem with many of these files is that they may be made up of many, many special colors (I have seen 16 special colors on one job!) and many, many layers. Typically, the file you want to end up with will have to be a collapsed file with maybe one or two special colors, or a file that is made up of as little as two or three plates of colors. This is a far cry from the multitude of colors of the original file. One would think that you could go back to the Illustrator file and have the designer redo the file, but this would be like pulling teeth typically unheard of! Many designers have no concept of the print process, and as such, they don't build files that are print friendly.
Now that we have our image in Photoshop, we can begin to check the image and perform the necessary corrections.