Pixelicious – working with Jpeg Files

Pixelicious – working with Jpeg Files

There are so many file formats out there. Jpeg files are among the most common for photography. Jpeg is a standardized file format created by  the Joint Photographic Expert Group (which is where it’s name comes from).  Jpeg was standardized in 1992, so it is a very mature standard, and probably could use a little updating, but part of the problem is that no one wants to deal with the problems that a new standard would cause. I guess we are stuck with it for a while. Everyone loves jpeg for its broad compatibility and ease of use. I have never been a big fan of jpeg files just because of the lossy compression.

Lets get at the heart of the pros and cons of jpeg file format.

Cons

Lossy Compression Blocking artifacts at low bit rate No lossless capability

Pros 24 bit color high details & high quality pictures reduced file size it is the most used graphic file format approved as standard in 1994 standard file format. broad range support

From the pros/cons list, it may seem that the pros outweigh the cons, and for some uses that is true only because this is not currently a better alternative. The problem is that we are all very impatient. We will not wait for a file to load, so jpeg was created to share images on the web at an acceptable quality level while making the files very small. Every time a *.jpg file is saved it compresses the file to save space. When you save a file you are given a choice on how much compression to apply, the more compress the lower the quality. Every time you save it, the file, will loose a little (or a lot ) of information. That is one of the problems that many do not quite understand; Every time you open and then save a jpeg file, some of the data of the file is lost.

You can see the effects of over compressing an image using jpeg, on the left the image is full resolution jpeg high setting, on the right is the same file set to the lowest quality - highest compression. Notice that almost all fine detail has been lost in the right image.

You can see the effects of over compressing an image using jpeg, on the left the image is full resolution jpeg high setting, on the right is the same file set to the lowest quality – highest compression. Notice that almost all fine detail has been lost in the right image.

There is no good alternative for the professional/enthusiast photographer because everyone wants their images delivered in jpeg format. But, there is a workaround. I shoot raw files from the camera (more on that in an upcoming post). Once the raw files are edited I burn them to jpeg, and that is how I used them – basically – as finished files that will not be edited or changes. If I need another copy of the file at a different resolution I will make a new copy from the original with the new dimensions. I always work from the raw files, Lightroom gives me an easy way to work non-destructively, and still deliver quality files that meet the requirements of each application without over compressing the final results. The trick is often to reduce the pixel size to the smallest size that will work, and then use the highest quality compression that you can when creating jpegs for final use. For most of my web use I end up using 1500 pixels on the widest side and setting the jpeg compression to 9 or 10, this makes reasonable sized files that will load quickly enough, but still look really good on screen full size.

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