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Image quality vs. size

  • Have you ever wondered about the difference between DPI and PPI and how they relate to image quality? Do you have trouble figuring out what size an image needs to be so that it looks good in your printed materials or on your Web site? Do you have other image-related questions that you just can't seem to answer?

    TechSoup's article Understanding Images: A Guide to Resolution and Size answers a few of the most common questions regarding image quality and size.
  • Great work!
  • Hey Don,

    Thanks for the kind words; Senior Editor Alexandra Krasne and Associate Editor Willow Cook both played a major role in helping sort this article out; it's a deceptively complex subject.

    Brian Satterfield Staff Writer TechSoup.org
  • This is probably the best article I have read explaining image resolution. I plan to keep it on file. I'm a graphic designer and have noted in other articles I have read on the topic that the ppi vs dpi isn't addressed or the writer is unclear on the distinction between the two. It's confusing when even on scanners the resolution is referred to as dpi when dpi refers to printing resolution, not image resolution.

    In terms of creating documents with images for print or web, another article may be in order: describing not only press resolution vs web resolution but also rgb vs cmyk. For instance, people trying to do their own pre-press work wonder why they can't see a jpg sent to them as it doesn't automatically open in their emailer. That is likely because the jpg is in cmyk format and so needs an image editor software in order to view it. Once converted to rgb it will show up in your email without you needing other software to open it.

    With charities and non-profits a graphic designer is not always affordable and so a few basics for the lay person may come in very handy.
  • Maddi,

    Thanks for the kinds words. I'll be the first to admit that it took me a LONG time to grasp the difference between PPI and DPI, which is exacerbated by the fact that so many programs (and articles on the Internet) use the two terms interchangeably.

    As for your suggestion on an article about RGB vs. CMYK, that's an excellent idea. We were toying with including this information in this article but thought we should stick to resolution. I'll work with the rest of the content team about getting this kind of article together.

    Brian Satterfield Staff Writer TechSoup.org
  • Maddi,

    Thanks for your excellent suggestion that we produce an article on color formats. It can be found here:

    http://www.techsoup.org/learningcenter/software/page6124.cfm

    I hope you and the rest of our readers find it useful.
    Brian Satterfield Staff Writer TechSoup.org
  • Hello!
    My name is Ellen and I am the new kid on the block. I am doing some research for my organization, as we are in the process of collecting info for our own in-house photo studio. We are are looking for a way to document our work and also possibly use some of these images in our promotions as well.

    Right now, I am focusing on what would be the best camera for us to purchase. I have recently purchased a Canon Rebel XTi for myself, which has 10.1 megapixels. However, I know that my employer would like to keep the costs to a minimum. Would say, 8 megapixels be sufficient? Does anyone know what the maximum image (print) size for a camera with 8 megapixels is? The article made sense, but what if you haven't bought a camera yet and thus have no image dimension info? How then does one figure that out? Is it even possible? The type of camera we purchase will be dictated by the maximum image size possible. Can anyone help me?

    I apologize for being so long-winded and for being so technically challenged. Thanks in advance for any insight you may be able to share! :)
  • I suggest you give the following article a read:



    Epinions Article On Digital Cameras

    Tim Claremont
    Systems Administrator
    Rochester, NY