| | Extracting the Thumbnail from the PhotoShop private TIFF Tag |
 | | Both have a unique ID. PhotoShop 4.0 used to write the thumbnail in a resource with ID 1033, PhotoShop 5.0 and upward writes the thumbnail in a resource with ID 1036. |
 | | However, some applications may choose to reject thumbnails that are, for instance, too small for their purposes, and the early indication of thumbnail width and height may allow them to do so without setting up JPEG decoding structures first. |
 | | This means that, when having decoded thumbnail resource 1033 to a RGB raster with your familiar JPEG library, you need to next swap the R and B channels. |
| www.awaresystems.be /imaging/tiff/tifftags/docs/photoshopthumbnail.html (760 words) |