We all love to take pictures – it’s so easy with digital cameras. Those digital pictures are oftentimes saved in JPEG format, and some may be surprised to learn that the JPEG format may actually lose image quality each time a file is opened and re-saved. (Kind of like the degradation due to repeatedly making poor quality copies of a paper image and its copies.) This loss can be significant, depending on the software and its settings. Furthermore, some may have even heard that simply rotating a picture 90o (e.g. from portrait to landscape) while viewing it in Windows also degrades the picture quality. All of the above is true and could be a cause for concern for serious photography buffs.
For that reason, I set the camera’s image quality to “best” to obtain the highest quality JPEG original. If rotation is required, I subsequently make a copy of the original picture and rotate the copy – that way I retain the original at the best possible quality supported by the camera – because image degradation due to information lost as part of the rotation process can never be restored.
But that process provides an awkward solution. It’s much easier to solve the problem by using a “lossless” picture rotator utility which does not degrade picture quality. I’ve adopted JPEG Lossless Rotator based on family recommendations. (See #35 in the qualified software list. Note that Photoshop is not included in the list.)
See this link for a more detailed discussion of JPEG format’s limitations, benefits, and uses.
All that being said, JPEG remains a very popular and useful image format. I’ve been unable to visually discern significant degradation over two or three “open-edit-save” cycles at highest JPEG quality settings and normal on-screen views using simple photo editors. I’ve even been able to blow up some of the resulting images to poster size and still have it look acceptable. Perhaps not professional quality, but acceptable for a layman.
But good quality is not guaranteed every time, even at the highest JPEG quality settings. A JPEG image’s quality depends on the original image quality as well as the history of the file: How many times, with what software, and at what settings the image was re-saved in JPEG format.
All is not as it looks.