Hi Res photos & artifacts

This discussion group is is hosted by Robert Oehler and dedicated to the art of photographing models. Subjects include tips & techniques, equipment, lighting, and digital photography.

Hi Res photos & artifacts

Paul Krylowski
Paul Krylowski

July 23rd, 2003, 3:23 pm #1

I own an Olympus C5050, 5 megapixel. I want to shoot high res photos and have used the Tiff or SHQ 2560 x 1920 settings. I open my photos in Photoshop directly from the camera and notice the file length is over 30" wide but only 72 dpi. Is this a Photoshop limitation or camera thing. I would think the photos s/b 8"+ wide and 300 dpi. If I rescale them to 300 dpi and 7" wide they appear hi res.

My other question is artifacts and distortion. I shoot at 64 ASA, F 8.0 and 1/1000. I notice graininess in the images and they are flat. Bumping them up in Photoshop really helps along with using the Unsharpen mask filter. I will need to experiment further but if anyone has some suggestions I am willing to listen.

Any help appreciated, thanks

Paul
Quote
Share

Brian Dumas
Brian Dumas

July 29th, 2003, 6:43 pm #2

Photoshop will open files the way they were saved from the native device or application. The camera saved them out using a default setting which Photoshop interprets as W by H at 72dpi. When you make the image size adjustment in Photoshop make sure the resample image box is NOT selected. That should scale the physical size of the photo down to whatever resolution you selected. You can also save a bit of memory by saving them at 212dpi, 300 would only be used for a high-end print run using a high line screen, a photo journal like National Geographic probably uses 300 since all there stuff is high-end photo reproduction.

As for artifacts; Not knowing anything about the camera I really can't be sure. I suspect the camera uses some type of compression scheme for the images which causes some dithering of the image (that's the program trying to simulate the pixel color of a given spot by sampling the surrounding area and averaging it out). If you have the option, try to avoid using any compression at all, but if you must compress use LZW compression since it is a lossless method.

HTH.

BAD
Quote
Share

Paul Krylowski
Paul Krylowski

July 29th, 2003, 8:04 pm #3

Brian,
Thank you for the info. By not using the Resample box, I assume the image will retain more of it's original pixel information? I will give your suggest a try.

Paul
Quote
Share

Brian Dumas
Brian Dumas

July 29th, 2003, 11:40 pm #4

Correct, once you've deselected that box, then enter the resolution you want, Photoshop will then scale the image to the actual pixel dimensions using the resolution you entered. If the box is checked, it will dither it to make up for the missing data and that creates bitmapped images (blocky appearence with hard edges) and artifacts.

BAD
Quote
Share