Occasionally, I want huge prints such as 40 x 60 inches, and I found an online lab that is reputed to provide excellent results. Surprisingly, they do not accept anything but JPEGs and only if they are 25 megabytes or smaller in size. All of my TIFF images are much, much larger. Is it really possible to get good-quality big prints from JPEGS, especially when the files are so small?
Well, Irvyn, a 25-MB JPEG—when closed, in its compressed state—becomes a massive file when it’s opened. So the lab will actually be using huge images when making the prints. Do not confuse the size of a photo when it’s open (un-compressed) to the size of the file when a JPEG is closed (compressed).
For example, save a 104-MB photo from a Nikon D810 at Level 12 (least compression = best image quality) in Photoshop or the 100% Quality option when exporting the photo in Lightroom. The saved JPEG will be only 11.4MB in size when it’s closed. If you own software that does not provide compression levels, it probably employs equally gentle JPEG compression. While the TIFF format would be preferable in terms of maximum image quality, a TIFF photo compressed with LZW is about 47 MB in size when closed. Frankly, it’s not practical to upload files of such size.
Perhaps you have image files that are much larger, such as 300 MB, achieved with focus stacking or another composite technique. In that case, use JPEG compression level 11 or the 80% quality option in Lightroom, and the massive file should still be under 25 MB when closed. And this level of compression maintains excellent image quality. Since few photographers have files larger than about 105 MB (when open), the least amount of JPEG compression is highly suitable for images they plan to upload to an online lab or stock agency website.