It is somewhat a myth that every time you save a file as a .jpeg that you lose information and compression occurs. For a long time, many photographers have assumed that if you save your file as a .jpeg that you are losing a lot of data. You may…or may not.
Some truths about JPEG:
For many years, there has been controversy surrounding the use of JPEG. About 5 years ago, programmers (not photographers) were brought in for an in-depth study into the fine data mass of JPEG files and were able to shed some light into their use.
- You only re-compress the file if you save it as a new file, not if you just click ‘save’.
- If you open a file up, i.e. called “Apple” and hit save, it will save the data with the modified changes and there will be no compression or loss.
- You could hit save a million times and it would still be the same exact data as the original.
- If you click ‘save as…’ and re-name the file to “Apple 2″, you have compression and loss. Click ‘save’ and no compression.
- Now you take “Apple 2″ and ‘save as…’ “Apple 3″, you will have compression again.
- The compression ratio is 1:1.2 so you only get about 5 re-saves before you’ve lost enough quality to be noticeable.
- Also important to note, JPEGs do more than compress the file, they also lose color and contrast range.
- These numbers and ratios are examples for the sake of easy explanation, but lets say a picture has 100 colors and 100 contrast points. A RAW or TIFF file will record all 100 colors and 100 contrast points. However, when the picture is shot as a JPEG, the camera kind of does a little post-production and edits the image for you. The JPEG will only capture say 85 of the colors and 90 of the contrast points. Now the actual ratio and loss is variable depending on the picture and there is no set formula, but the essential summary is; if you shoot in RAW or TIFF you are getting 100% of the data. If you shoot JPEG, you not only loose colors and contrast but then get a 1:1.2 compression. This is also true for if you take a RAW or TIFF file in post-production software and save as a JPEG, it will do the same color/contrast loss in addition to the compression of the conversion. Most often, its not visibly noticeable. There is no loss if you copy and paste a file from one drive to another too, but your metadata will be altered. This comes into consideration if you want to ever prove ownership or enter a contest. Many contests now are requiring the original file as proof of metadata/ownership.
How Should You Save Your Images: Is JPEG Acceptable?
Start by reading this article and the comments on WHAT IMAGES TO KEEP VERSUS DELETE so you are familiar with the terms.
- If you are shooting “documentation” shots, especially casual family or party shots, then shoot in JPEG and keep them as JPEGs.
- If there is any chance you are going to capture something “great”, then shoot in RAW. Then when you save the file, you have to save 3 copies: the original RAW file, the edited/layered file (TIFF, PSD, or PNG, your choice), and then a JPEG version of the edited file for more versatile uses.
- I personally go one step further and save a 60% compressed JPEG as well, for use on the internet. This is so I can use it on websites, albums, etc. and not worry about someone stealing a full size copy. I never publish anything online that is full size, even people shots. Not only will it reduce the amount of space you take up on the site, but if there is ever a dispute, its simple; I have the only full size version.
“But it takes up so much room!”
I often hear this from people. The problem with most photographers today is they don’t anticipate what they may want to do with their photos 5 or 10 years from when they start taking photos. By the time you’ve learned that you want all those files, it’s been years of thousands of shots that you’ve taken and won’t be able to recover or convert if you skimp early. So yes, it does take up a lot of space, but quite honestly, hard drives are cheap when compared to the cost of wishing you had kept certain versions or the time it would take to now create all those versions en-mass.
You’ve spent thousands of dollars on your equipment to capture and use images that will mean something to you for the rest of your life, $150 more to store another 50,000 files should be a no-brainer.
Chris Hartzell has over 3 decades of traveling and photographing in more than 20 countries and his work can be found in international calendars, advertisements, magazines, and educational exhibits as well as leads field workshops, wildlife tours, and teaches photography classes. You can see more about him and his work at his site, PhotoStrokes.net
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