file sizes

Hi all:

I use the Canon PPS for my processing at the moment...don't have anything else. My question is: when I'm required to reduce a file to 250KB or smaller I have to resize to very small dimensions, such as 450 pixels on the longest side. I've heard that Photoshop does something with compression when saving so the photo can be sized larger for the web or contests etc...is anyone out there who can tell me if there is a feature like this in the Canon software that I haven't found yet...like a save for web function that will make a small file, but larger dimensions? I've looked the "zoom browser" and in the "convert and save" function that resizes in PPS.

Thanks,
Cynthia

Are you talking about DPP (Digital Photo Professional)?? I don't know what PPS is. If you are using DPP, you can chose File / Convert and Save. That will bring up a dialog box that allows you to save as a JPEG (among other file formats), choose the dimensions, and the output resolution. For NPN, you need to save with the long side no more than 720 pixels. Save it a 72 DPI and you should have a file size that isn't too large. There is an image quality slider that will help with the file size as well.

I don't know anything about PPS Cynthia, but all programs that save JPGs should have some kind of "quality" setting. Usually it's a percentage or a numerical scale (like 1-10 or 1-12). Between resizing your file to the dimensions you want, using this quality setting is the normal way to get the file size small enough. The only extra thing the "Save for Web" feature in Photoshop does, is strip out the extra information that may not be needed - camera data, and the color profile. Sometimes they can help, but there's no reason you shouldn't be able to save almost all images at 720 pixels on the long side, and a reasonable JPG quality in any program.

Per what Keith said.....72 DPI is meaningless. This only affects devices that work with inches, like printers. A 720 pixel file is completely identical whether you set 72 DPI, ro 72000000 DPI. The pixel dimensions are all that matter. Save it at 720 pixels, and adjust the quality to get what you want.

Thanks guys...you're right I had the acronym mixed up it is DPP...I was thinking "photo professional software" I guess. I did notice the quality slide in "convert and save" and it is set at 10...so if I reduce this the files should be smaller, that is good to know...I always wondered how anyone could submit a larger size and still keep it under the KB limit...because I never could, and I didn't want to sacrifice any quality.

Does anyone know a reasonable number to start with or not go below before it starts looking bad? Maybe 7...I know it depends on the file size of the photo...but just curious in general.

Cynthia,

I'm not familiar with the software you guys are talking about, but typically most "save-as" dialogues will include or indicate the expected file size. In other words, you can change the quality setting and the program should tell what it's going to be, without actually having to save it to find out.

Hopefully you already know this, but in case you don't... When you're working with jpg files and "save" the file, data compression happens onthe file (which is how the size can be reduced.) This "data" is LOST. Once you save a jpg, you can't get any of that data back. So, you should always work from a COPY of your original. I'm not a digital shooter, but I believe most folks save a "master" copy of their captured images; regardless if they shoot in raw, save to TIF or in Photoshop's PSD format. If you're shooting jpgs, then ALWAYS save a master and do your work, processing and resizing on a copy of that master.

Hope this helps,
Lon

I've never understood why this is such a difficult concept, but since it comes up so often I've written up a short tutorial on my web site to cover the basics. Just click on the "File Size Basics" header to expand the article. Although this uses Photoshop to illustrate the steps the basic concepts apply to any program.