Images For The Web – An Argument For Lower Quality Cameras

Background
I have prepared thousands of jpeg images for the web. This includes the images I have posted here on Photograph Works and those I have prepared for Quillcards. There are also other sites to which I have uploaded images. So, all in all, I can definitely say it is something I have done a lot of.

The Problem
As a result, I have a pretty good idea of which images are going to cause a problem, even before I start to prepare them.

By ‘problem’ I mean that the file size of the image is bigger than I would like.

If the images are on my website on a commercial web-server, then the bigger the file size of the images, the slower the pages will load. Slow load times lead to bad visitor experiences.

Of course, sometimes it doesn’t matter how big the files are. The servers on Flickr can deal with more or less anything and still get the page to load quickly. For the rest of us, load on the server is important, and images with large file sizes can be a big drain.

Jpegs
The whole point of jpegs is to save file size by compressing images to save and store them and then uncompressing them when they are viewed. They work by making dividing the image into blocks and referencing adjacent parts of the image relative to the information in the block. If the adjacent part of the image is similar, then the information needed to record it is small. If the image adjacent to the block is not similar, more information is needed to record it. More information means more file sizes.

A Quick Look At The Process
Let’s just take a quick look at the process of preparing images for the web. There are, of course, different programs you can use. Some, such as Photoshop, you have to buy and some, such as Gimp, are free. There are also web-based solutions such as shrinkpictures, which is free to use for single (as opposed to batch) processing.

I use Save For Web And Devices in Photoshop. If you haven’t used it before, you will find it by going to ‘File > Save For Web And Devices’. If you try to save a big file then you may get a warning to the effect that you are using a file that is bigger than Save For Web And Devices was designed for and that you might get memory errors or slow performance. Despite this, I have never had a file that has caused a problem.

I use Save For Web And Devices because it strips out the metadata and because it uses subsampling and downsampling intelligently and automatically. Check out the link for more information on this. Finally, I use it because it makes the smallest, best-looking images I have been able to make with any program I have tested.

I have heard that Adobe’s Fireworks does an even better job of reducing file size while retaining quality. I did ask around about this but I have never seen examples that prove the point. So for the moment at least I use Photoshop. I have tried yahoo’s Smush It to see whether I could reduce file size even further, but this usually shaves no more than 2 or 3 per cent off the file size, and on a 40KB file that doesn’t amount to much – not enough to make me want to use it, anyway.

What Big Files You Have, Grandmother
So what files cause problems? As I said, if the adjacent part of the image is similar to the sampled block, then the information needed to record it is small. If the image adjacent to the block is not similar, more information is needed to record it. So a photo of a person standing against a blank wall will compress to a smaller size than an image of bushes and trees with variegated leaves.

And The Argument For Lower Quality Cameras?
My main camera is a Nikon D700. My ‘carry around’ camera is a Nikon D60. The Nikon D700 takes better shots of landscapes than does the D60. This is because the sensor is better and it captures more detail. The downside is that when I Save For Web And Devices with the D700, the file sizes are substantially bigger. It doesn’t matter what method I use to reduce the file size.

I have tried saving the files by first reducing the image size and saving as ordinary jpegs and then using Save For Web And Devices. Nothing works. The files are bigger to begin with and they stay bigger.

So the question is, what is lost by using a lower quality camera that captures less detail, when the image is only ever intended to be shown on the web. At 500 pixels wide, can one see the difference? Can you tell which camera I used to capture the image at the top of this article? Was it the D700 or the D60?

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