Can someone explain resizing for printing?

fclark

With my old p&s camera I always shot in the highest resolution possible, then when I sent pics online to print, uploaded the file straight from the camera (or from PS if I adjusted anything) and cropped if necessary on the printing website. If I cropped the picture beforehand, I set it to the preset 4x6 crop size.

I've been reading mentions here and other places now that seem to say that I'm supposed to be resizing or change ppi for each different size of picture I'm ordering? I've tried to search to understand what I"m supposed to do, but I can't seem to find the whole answer anywhere.

Would someone be kind enough to explain what I should be doing with pics from my Canon Digital Rebel XT when I'm ordering prints online?? Thank you!

Jeffro

The online sites I have ordered from have always done the resizing before printing, so unless you want to print at home, at the right dpi and all that, I'd just upload the entire file, then crop online if need be, because any good online print service will allow you to crop for different size prints, or whatever reason.

My 20D generates a 72dpi file, which I load upthe full file, and people can order whatever size they want....the prints look great, so something is being done right, somewhere, by someone.......

meewolfie

I'll give it a try...
Resizing assumes that you will be bringing the photo into an image editing program. I'm going to explain how I do it in Photoshop CS2.

1. You will download your image from you camera. Let's say that you are shooting in the largest size, so this "direct from camera" photo will be 3456 x 2304.

2. The next step will be to make any adjustments if necessary to the image. Contrast, color, sharpening, etc. Finish all necessary retouching work and save a copy of the image at full quality. No resizing has been done yet.

3. Decide what size print you will want. Let's say that you would like to print a 4 x 6 and an 8 x 10. If you compare these sizes, you can see that one has a width to height ratio of 2:3 and the other has a width to height ration of 4:5. If you were to make only one crop of your image to one of these ratios, the other size print would have to be cropped by the ordering system - and this crop might not be ideal. This is why cropping and resizing them into two different files ahead of time makes sense. (YMMV - depending on the composition, etc. If there is a large area of blank space in the photo, then post-upload cropping may not be that critical of an issue.)

4. Open a copy of the photo that you saved in step 2 and select your crop tool at the 4 x 6 preset (or create the preset size yourself if it isn't already available) and set your pixels to 300 (or whatever you would prefer). The crop tool will constrain itself to a 2:3 ratio. Choose the area of the photo that you want to see in your 4 x 6 frame and crop to that area. Photoshop will then resize the image so that the newly cropped file is exactly 1200px x 1800px (assuming you chose 300ppi).

5. Save the 4 x 6 cropped file with a meaningful name.

6. Take another copy of the file that you saved in step 2 and reselect your crop tool. Change the preset dimensions to 8 x 10 and the ppi to your preference (using 300ppi again in this example).

7. Now the cropping tool will be constrained to the proper proportions for an 8 x 10 image. You can control how you would like to crop the image. When you apply the crop, Photoshop will then resize the file to 2400 x 3000. Save a new copy of this one with a meaningful name.

Now, when you upload those two images for printing, you should be able to get a print that looks exactly as you expected. If you were to try to order a 5 x 7 from the file that you cropped for an 8 x 10, you would have to use the less-user-friendly cropping tool provided by the online ordering system to select the portion of the 8x 10 cropped photo that would fit in the 5 x 7 frame. Better to control the crop before you upload.

If you were to upload the straight image to online ordering system, they will crop and resize the image for you based on the print size that you order. The downside is that you may not get the picture that you expected.

I hope that explanation makes sense. I made an assumption that you know how to save your files in the correct formats and have a basic understanding of the cropping tool. If more details are required - or if you need clarification - let me know!

Mary

meewolfie

Ok, so Jeffro's answer was a little bit simpler!

Basically, the printer can do the work that I described or you can do it yourself ahead of time.

It probably depends on who will be ordering the prints. If I was uploading prints that someone else was going to order, I'd definitely do the resizing ahead of time so that they wouldn't have to worry about cropping at all when placing their order.

If you're simply uploading the images for yourself, then you can pick your crop at order time and not worry about fussing around ahead of time.

I've used some ordering tools that make it easy to select a nice crop, some aren't as user friendly. You could always try it out each way and figure out which works best for you!

Mary

fclark

Thanks!
Thanks so much for the repsonses! This is basicalliy what I have been doing - letting the printing company worry about the size of my files. I'm working on a wedding that I did last weekend for a friend and I've been pre-cropping everything to 4x6 so I don't have to do all 200 or whatever of them online!

Thanks again.

BinaryFx

I hope that this PDF can help explain this confusing subject:

http://www.ledet.com/margulis/PP7_Ch15_Resolution.pdf