Thread: If I save my files as JPEG, do I lose q...

I never use in-camera jpegs - always work from the RAW file. Perhaps that has a specific bearing on what others get compared to what I get? However, read on as I find his (Andrew Kelsall) methods unacceptable. I certainly do not see the degradation shown in that article. I would also suspect his problem was saving at different jpeg levels, which he mentions. I can certainly believe a loss when someone is daft enough to save at different...

Yes. Use widely supported lossless format like PNG if need to do multiple edits. Aristoc wrote: > I have photoshop 6. After editing a photo and opening and saving it several times as a JPEG/JPG am I going to lose some data/quality from the photo? >

Not quite true. ianR wrote: > Yes, jpeg is a lossy format but that doesn't mean it MUST lose data, only that it will prioritize file size over accuracy if you want it to. It does lose information, no question of that. However, the lost information may not be visible. > The more you compress the more data is lost, not the more times you resave. It really only becomes noticeable around about the 87% mark though, whatever that...

Congratulations. If you cleaned installed Win7 then you could've partitioned the drive in the beginning. Or could've just installed and then manipulate the partition afterwards. Two hours to intall Win7 itself?

I definitely get different results here. On the left a cropped portion of a jpg straight out of a Canon 500D (L jpeg quality). On the right the same portion after some editing (1 pixel crop to the original), saving, closing, opening the newly saved and re-applying the process for 10 times. jpeg quality was set to 90% for each iteration. Quality loss is obvious: artifacts, false colors, less detail etc. Especially shadows suffer a lot....

Compression technologies used by stacker, or more recent compression algorythms like zip or rar are *lossless* algorythms. You can compress and then expand files using these algorythms a billion times over, the resulting file will still be 100% identical, bit for bit, to the original. The jpeg compression algorythm is a *lossy* algorythm. It's /designed/ that way, in order to achieve higher compression rates. It's designed...

Agree totally with your findings, sure if you continue beyond 10 , say to 30 there will be a difference, I've carried out similar tests at a camera club with others taking part and results concur with yours, we even did the old raw/jpg comparison for quality and again no difference (that anyone would put money on) in prints. Carl

the theory says that if you resave a jpeg enough times you get a image degradation. why would you do this enough times to make an issue of it? i shoot jpeg all the time, well 99.9%, and never have a problem with the image quality of jpegs. what i do is bypass the issue altogether by simply doing a save as a tiff after any pp and sharpening. all future work is done to the tiff, the jpeg is never touched at all. the original jpeg is simply put...

Yes, jpeg is a lossy format but that doesn't mean it MUST lose data, only that it will prioritize file size over accuracy if you want it to. The more you compress the more data is lost, not the more times you resave. It really only becomes noticeable around about the 87% mark though, whatever that relates to in the program you're using. The more you compress the smaller the file size you get at the end and that's the real proof...

I have photoshop 6. After editing a photo and opening and saving it several times as a JPEG/JPG am I going to lose some data/quality from the photo?