EBL,
You are definately working in RGB/8, not indexed? If you are your file sizes will be a quarter of the ones below.
Open cropped CR2 file (size 6.62 MB; 3504×2336 dpi)
These are pixels and have a "memory debt" of 8.18 MegaPixels (same as your camera?)
Convert to 8 bit
Details at this point (2114×2935 pixels; resolution 762 pixels/in)
= a "MB" of 6.29MegaPixels. In Photoshop, a new image of these dimensions has a pixel dimension of 17.2MB. If you then reduce the longest side to 768 pixels constrained, the other side will be 553 pixels. At 762 ppi resolution, this will give you an image of 1.008 x 0.726 inches. This gives a pixel dimension of 1.22 MB before compression. These values will differ depending on the complexity of the image.
See below CS2 Help file}
Pixel dimensions and image resolution
The number of pixels along the height and width of a bitmap image is called the pixel dimensions of an image. The number of pixels per inch (ppi) printed on a page determines the image resolution.
The amount of detail in an image depends on its pixel dimensions, whereas the image resolution controls how much space the pixels are printed over. For example, you can modify the resolution of an image without changing the actual pixel data in the image-all you change is the printed size of the image. However, if you want to maintain the same output dimensions, changing the resolution of the image requires a change in the total number of pixels.
Pixel dimensions equal document (output) size times resolution.
A. Original dimensions and resolution B. Decreasing the resolution without
changing pixel dimensions (no resampling) C. Decreasing the resolution at same document size decreases pixel dimensions (resampling). In Photoshop, you can change the resolution of an image. In ImageReady, the resolution of images is always 72 ppi, to optimize the images for online media.
Example of an image at 72 ppi and 300 ppi
When printed, an image with a high resolution contains more, and therefore smaller, pixels than an image with a low resolution. Higher-resolution images can reproduce greater detail and subtler color transitions than lower-resolution images because of the density of the pixels in the images. High-quality images often look good at any print size.
You can’t improve a lower-quality image by printing it at a high resolution. Changing the print resolution of an image simply makes each pixel larger, which results in pixelation-output with large, coarse-looking pixels. Increasing the print resolution of an image doesn’t add any pixel information to the image. You can make a low-resolution image look its best by picking a print size that makes the most of the pixels it has. Important: Video files are displayed only at 72 ppi. Even if an image has a higher resolution than 72 ppi, the quality may not be very good when it’s displayed in a video-editing application.
Printing the same low-resolution image at different sizes
A. Small print size B. Medium print size C. Large print size
File Save As (or Save for Web–no difference) Choose JPG. Change quality slider to 12
Maximum size is 232K
I know I’ve done this before, and would use ~10 or 11 for file size up to 500 (again maximum allowed for submission).
I want to increase the quality as much as I can–any suggestions?