Grainy Photos

Joined: 21 Apr 2005 Posts: 19 Location: american fork, ut

Hey all,

I have what is hopefully a simple and straightforward question. I use a Canon 350D digital camera and use the RAW format option on it. I believe I usually leave my ISO settings at 400....I tend not to mess around with it too much.

When I load the pictures onto my computer and use a generic picture-viewing software, they look great. Then I decide I want to crop them a bit and print them, and I load them into Photoshop CS. The image size shows up as 32x48, which is fine with me. No problems so far.

Obviously I want a smaller print, so I'll do a bit of cropping and then shrink them down (the width-height ratio is locked, so they're hopefully not getting distorted in this way) to 4x6.

I've also tried doing it the opposite way, shrinking them to 4x6 (which is still proportional to 32x48 obviously) and then cropping anything that I need to.

The problem is that when I do this, the photo ends up looking grainy and/or out of focus on my screen as well as on the print. It's not the worst ever, some people don't mind, but it does bother me and would certainly be bad enough to bother most people who take pictures regularly.

I'm not super familiar with photoshop beyond the crop, resize and sharpen options and don't generally mess around with the photos too much. Is there something i'm doing wrong, or is there a better way to resize photos than this? Perhaps a resize option in the camera?

Any help would be greatly appreciated.

Joined: 28 Jan 2007 Posts: 3

There are two ways to consider image size. On your computer screen, the image is displayed based on the number of pixels in the image. If the image is 3800x2600 pixels, it will be larger than your 1280x1024 monitor by far and you will have to view the image at a reduced size in photoshop to see the whole thing.

However, when you print an image, the pixel dimensions aren't as important. What is important is the document size and the ppi or pixels per inch.

If your image is 1000x800 pixels, but the ppi is 100, it will print as a 10x8. Change the ppi to 200, and it will print as a 5x4. Both pictures will have the same number of pixels and be the same size on your screen, however.

If you make any changes to the ppi or document size that affect the number of pixels then your image is getting enlarged or reduced and this can lead to loss of sharpness.

Most printers generate a fair quality image at 250 to 300 ppi. Web quality images are 72 ppi.

When you say your images are 32x48, are you referring to the number of pixels? That sounds like thumbnails and not the real images.

When you take a RAW photograph, you don't have a real image until you convert the RAW file to another format, such as jpg. A RAW file is like a digital negative and it is just a collection of data captured by your camera sensors with no camera processing, such as white balance and color profiles and so on. When you convert the RAW to a jpg, using something like Adobe Camera Raw plugin, you set the white balance and other adjustments that your camera would have attempted had you taken the photo as a jpg.

Your ISO determines the sensitivity of your sensor in your camera. In direct sunlight, you want it about as low as it will go at 100 and in a very dark place you would want it higher, like 1600 or 3200, depending on your camera. The higher the ISO, the higher sensitivity of the sensor to compensate for less light, but also the more noise you will get in your images. It's good to keep your ISO as low as you can, but don't be afraid to raise it when you feel you need to.

Can't remember CS's capabilities regarding RAW since I've been using CS2 and CS3 for awhile now.

I hope this helps.

Joined: 21 Apr 2005 Posts: 19 Location: american fork, ut

Thank you Harkain. I understand the ISO bits and what not, but wasn't aware that I should change the PPI instead of the actual image size in PS.

Is there a way that you are aware of to change the PPI to change the size of the printed image? If not, I will tool around with it when I get home and see if I can figure it out. Thank you again, I think that may be the solution I was looking for. I was just doing a straight shrink of the image from 36x48 or whatever to 4x6, thinking that it would not lead to loss because it was shrinking the size. I will shrink it down using the change PPI option if I can find it and report back. Thanks again.

Joined: 21 Apr 2005 Posts: 19 Location: american fork, ut

Thank you Harkain. I understand the ISO bits and what not, but wasn't aware that I should change the PPI instead of the actual image size in PS.

Is there a way that you are aware of to change the PPI to change the size of the printed image? If not, I will tool around with it when I get home and see if I can figure it out. Thank you again, I think that may be the solution I was looking for. I was just doing a straight shrink of the image from 36x48 or whatever to 4x6, thinking that it would not lead to loss because it was shrinking the size. I will shrink it down using the change PPI option if I can find it and report back. Thanks again.