Image quality and file compression

print email Digital cameras store images in a compressed format called JPEG. JPEG is the most commonly used file format. Some cameras also have uncompressed formats (TIFF and RAW). [Digital camera file formats]

When images are compressed their file size becomes smaller so more can be stored on a memory card. However, if compression is set too high, image quality degrades.

Low compression = better image quality

For optimal image quality, select your cameras least compression and highest resolution (highest number of megapixels) settings. Digital cameras provide a variety of compression levels: Super Fine, Fine, Normal and Basic. The terms vary among manufacturers. The Fine or equivalent setting produces the least compression and best image quality.

Image saved at four compression settings - from left to right: none, high, medium & low

If you intend to print and crop images, use the least compression. But if you only plan to post images on the web, or send via email, using a higher compression is okay. Do keep in mind that you may decide later to print a photo, so it’s a good habit to use the highest quality settings most of the time.

An image can be reduced in size with image quality visually in tact. This is rarely the case if an image needs to be enlarged.

Image size/Resolution

The size, or resolution, of an image can be changed in a digital cameras.

Resolution relates to the size an image appears on a computer monitor, not the physical dimensions an image prints. For example, the available resolutions on a ten megapixel digital camera can be 3646 x 2736 pixels (10 MB) to 640 x 480 pixels (.3MB) and even smaller, with a number of different resolutions to pick from in between.

You may mix compression and image sizes on memory cards.

Click image to enlarge

Article tags

JPEG, Megapixels, Photo editing, Print size, RAW, TIFF

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On 7 January 2010 at 9:38 pm Carmel said:

Hi there
I own a Uniden Corporation UDC – 7 megapixel camera. I have been comparing ‘properties’ in other people’s photos and mine on flickr.com.
I have noticed some people have 8 compressed bits per pixel. My photos only show 2 compressed bits per pixel. Does this mean I need to work on my image quality? Where it has ‘compression’ listed in the photo’s properties it says ‘JPEG (old-style)’.
Thanks in advance for your reply.

On 8 January 2010 at 3:19 pm Gail Bjork said:

Unfortunately, your camera is not known for having good image quality. As far as I can tell from online specifications, you can’t change the resolution. Source: cnet-australia.

Two suggestions for getting better images: take photos in good — preferably outside — light and avoid at all costs using the digital zoom. Stick with the optical zoom.

On 10 January 2010 at 9:29 pm Carmel said:

Thanks so much for taking the time to answer my question. I’ll start saving for a better camera!

On 21 July 2010 at 12:47 am Lan said:

Hi, I have a canon 400D with Canon EF-S- 28-138mm usm f3.5-5.6 and 50mm f1.8. I have found no matter what lens i upgrade to, the image quality still remains the same. I use always use high resolution option with a high quality CF memory card, but always quite disappointed as the images always results similar to those of a compact camera- though image is not bad and in focus but they are not clean, sharp and crisp like those you would see on websites or magazines. I want to know how to make my images look clean and crisp like those on photographer’s websites. Can you advise?

On 21 July 2010 at 2:29 pm Gail Bjork said:

Lan, I experienced the exact same thing when starting with my Canon XSi/450D. I’ve written what I learned about it in this article, which I believe you will find helpful. Additionally, besides reducing an image in size and sharpening it, I often do a levels adjustment when I edit images.

On 21 July 2010 at 10:52 pm Lan said:

Hi Gail, thanks so much for a quick response! I read the articles and found it very useful. I will use the tips next I shoot. So in fact, is it true for me to say photos we see on websites and magazines is not what it originally looks like when it was first taken on the camera?

On 30 April 2011 at 6:12 am Jacki said:

Hi I have a canon 400d and i want to be able to take photos 640×480 so they are website ready but the smallest setting is 1936×1288. I know i can change on photoshop but i have stupidly already taken around 800 photos for the website and even before i resize i have to change to PDF format because i only have the first adobeCS version so i seem to have a nightmare ahead of me as far as resizing, re formatting and putting on to background so there is no obvious signs of borders! HELP! Is there a way around this and can i change the settings on my camera to take 640×480? Thanks to anyone taking the time to read my nightmare!!

On 30 April 2011 at 6:51 am Gail Bjork said:

Jacki, the 400D will not shoot smaller sized images. Try a program such as FastStone Photo Resizer, which is free. It will batch resize photos. According to the webiste, Version 3 also converts images to PDF files.