color depth of 8-bit and 24-bit color

hi!

need the following specs on a JPEG picture for an application:

(a) the image has to be 320x240 pixels
(b) the image should have a color depth of 8-bit color or 24-bit color.

here is what i tried:

after opening the file, i was able to do (a) by selecting "Image" and then "Image Size" and changing it to the required resolution.

am not too sure as to how i go about doing (b). i tried "Image" then "Mode" and then selecting 8bits/channel. is this the same as 8-bit color?

and finally, when i try and save as JPEG, there is an option for "image quality" on a scale of 1-10. will choosing a higher "quality" change the above specs i put into the picture?

many many thanks for your help!

ganesh.

JPEG only supports 24 bit color.

No, 8 bits/channel is not the same as 8 bit color (which is confusing).

8 bit color means indexed color (256 colors max).
8 bits/channel means 24 bit RGB, 32 bit RGBA or CMYK, etc.

Changing the JPEG image quality does not affect the bits or the image size, just the resulting file size and quality.