Whether you're readying PostScript artwork for online use or simply providing a colleague with a rasterized version of an Encapsulated PostScript graphic you crafted in Adobe Illustrator, you can use Adobe Photoshop to repurpose EPS artwork in the Portable Network Graphics format. This format-to-format translation requires no more time or effort than simply opening and saving a file.
Although EPS files can contain a mixture of live text, vector objects and bitmaps, most designers use them for non-bitmapped graphics. Unlike pixel-based images, EPS files rely on mathematical descriptions of the shapes they contain. As a result, you can scale their object-based code to very large and very small sizes without pixelation or distortion. EPS files that do use bitmaps, as placed images or in filters and effects, face limitations to their use at enlarged dimensions.
PNG originally was developed to replace the CompuServe GIF format by providing a patent-free alternative with fewer image limitations. PNG supports 24-bit color and anti-aliasing, yielding transparency without jagged background transitions in RGB and grayscale images, and can accommodate a wide range of other color modes, including bitmap and indexed color. Like GIF, it can't incorporate alpha channels. The lack of support for PNG in some Web browser software poses the greatest impediment to the format's widespread adoption.
EPS to PNG Format
To create a PNG version of an EPS graphic, simply open the EPS file in Adobe Photoshop. Depending on whether the EPS file contains only vector and text resources or also includes or consists of bitmaps, you may need to rasterize the file to open it. Photoshop automatically presents you with the proper file-opening options based on its analysis of the document you ask it to open. When the image comes up on your screen, choose "Save As" from the File menu. In the Save As dialog box, set the Format menu to PNG and choose an option for image interlacing, "Interlaced" for progressive image display as a file downloads to the user's Web browser or "None" to display the PNG file only when it finishes downloading.
If your EPS file uses live type, make sure your system offers the font files you need to support the text in your document. If your EPS file uses color and you must rasterize it to open it, choose RGB rather than CMYK mode. Otherwise, the Save As dialog box won't offer you PNG as a file-format option unless you convert the image out of CMYK mode and into one of the color modes that PNG supports: RGB, indexed color, grayscale or bitmap.