Raw pics / 40D / image size...question.

[simonB]

Background

After downloading raw pics with DPP (EOS utility) and transfering them to Photoshop CS2 I note that :-

- the image size is only 28.22cm x 18.81cm at 350 dpi.
- that the pixel dimension is 57.7mb (due to it being a 16bit TIFF file)

It says in the manual that both "raw" and "L" can be printed at A3 or larger

With the 20D I opened a raw image and could convert the sie to 52,02cm x 34,68cm at 300dpi on the canon software that opened it on photoshop.

Questions

What advantages does this size (57.7mb/16 bit) give me opposed to a "L" image with the same measurements ?

To enlarge the image, is it simply by changing the image size on photoshop rather than on canon software ?.....and if so How do you know when it starts to lose quality ?

Thanks to anyone who can help.

[tzalman]

Questions

What advantages does this size (57.7mb/16 bit) give me opposed to a "L" image with the same measurements ?

To enlarge the image, is it simply by changing the image size on photoshop rather than on canon software ?.....and if so How do you know when it starts to lose quality ?

The advantage of the 16 bit tif file is that it contains all the data captured by the camera and written in the 14 bit RAW. An "L" jpg is only 8 bits and it is also compressed. Both these operations, converting to 8 bits and compressing, cause the lose of part of the data. If you only do simple post-processing of the image - levels, sharpening, etc. - this is not so terrible. But if you want to do more editing, especially editing of the darker tones in the image, the tonal transitions will be smoother if you work with as much data as is possible.

The 3888x2592 pixels 40D image will fill an A3 at 235 ppi and will make a very good print at that resolution. Or you can resize it to 4960x3323 which will give you a 300 ppi A3. This is an increase of less than 30% and will not cause a loss of quality. PSCS2's Bicubic Smoother is very good for this. After resizing do your final sharpening.

[simonB]

Thanks for your time tzalman !

I´m off to experiment.

Was looking at the FAQ section which is also very helpful, this really is a great forum.