Photographs of a printed image appear pixelated

[lindamay]

Hi,
New to your forum and a novice digital camera user.
My question is a little general, as I am trying to understand interpolation and how it relates to pixelation in the resulting print.
I am trying to photograph small objects on a gradation background (black & white). I am creating the gradation in photoshop and printing it out, and the print looks just fine. But when I photograph an object on the gradation, the resultant image is pixelated where the gradation shows. The shot is taken at the highest resolution that the camera can shoot and the resultant image is a 28 megabyte file (9 x 12).
I have searched the forum to see if this has been discussed before, but found nothing.
I have an imperfect understanding of how the printer software interpolates the image you are tyring to print. I suspect that the printer driver affects the quality of the image to be laid down on the paper, given that the image dpi is 300 or less. I am not sure if I need to be focussing on the digital file or the printer itself when trying to resolve this issue.

Any help will be appreciated.

[Geoff F]

Unless I have 'grasped the wrong end of the stick' here, which isn't unusual. You have printed a background and are now attempting to photograph an object which has been placed onto the background and the background is looking pixelated.

If so, I wonder if it is a problem caused by the inkjet printer ink spot deposition. ie when making a macro shot your camera is seeing the actual ink spots.

What printer setting did you use when printing the background, I mean printer dots per inch not image pixels per inch on the computer. I suspect that for this to work you would have to print your background using the highest quality printer setting, say 2828 dpi. Even then you may still see the dots at high magnification.

I am thinking that you may need a totally solid drawn background for this to work successfully.

Hope this makes some sense, it's a bit difficult to explain and I'm not totally certain that my theory is correct here anyway. Let's see what the experts think.

Geoff.

[McQ]

Hi lindamay, welcome to the forums! Hope we can help. To me it sounds like the pixelated look is due to the printed background image and not the camera. First thing would be to try and get the printer to create a smooth gradient, but today's digital cameras often show the pixelated pattern in a print due to their high resolution -- even when the print was done at it's highest resolution and pixelation is not immediately apparent to the eye. Please include an example image in your next post if possible. That will make it much easier to diagnose whether it is your printer and what settings might need to be changed.

Something else to try, subject matter permitting, is to use a shallower depth of field so that the paper is slightly out of focus and the subject is in focus. This can be achieved either by using a large aperture (smaller f-number, like going from f/8 to f/5.6), or by increasing the distance between the subject and your printed background. Moving both the subject and background closer to your camera will also decrease the depth of field (even if the subject-background are kept equidistant), but this will also change the perspective.

[d3debian]

Because the first print is good i don't think the printersettings need to be adjust.
In my opinion the second file is very large (28MB) and it might have something to do about the file.
Is it a 16 bits file you are print on an 8 bit printer?
Can you try to convert it to an 8 bits jpeg-file and print again?

[Colin Southern]

Hi Lindamay - great to have you with us

Frankly I can't quite figure out what's going on - what I would like to do though is have a look at the file you're trying to print to see if I can figure out if the problem is the printer, or if the printer is only printing what it's told to.

If you'd like to send me a private message, I'd be happy to give you an eMail address and some instructions on how to send large files.

Hope this helps,