Estimating Sharpess and Quality at various print sizes.

1. The sharpness you can obtain in your prints is primarily determined by your camera. The more megapixels, the better.

2. Although you can expand your files in Photoshop to increase the megapixels, doing so usually does little if any good. The most common way of expanding files is linear interpolation between pixels. Via that method, the interpolated pixels add no detail. If you have an advanced program (e.g., Genuine Fractals) for expanding files, some detail is added. In that case, it is probably better for you to expand the files. If not, it probably easiest to let our system do that. We expand all files via linear interpolation to 300 ppi for printing.

3. Our system will give you recommendations for how large a print you can make from a given file. However, those recommendations are given with a caveat -- they are valid only if your file is sharp at 100% magnification. If you have expanded your file, it is probably not sharp at 100% magnification.

4. Required sharpness is very subjective. Generally, small prints are viewed at closer distances than larger prints, so small prints generally require a higher PPI. In general, for prints around 8 x 10 in size, a 4 megapixel camera is generally adequate. For prints around 20 x 30, at least 8 megapixels is recommended. For 30 x 40 or larger, 10-12 megapixels or more is advisable.

5. If you are adding text or line art to your file, then (everything above notwithstanding) you should expand your file to at least 150 PPI before you add the text. That won't help the image, but it will make the text sharper.

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