JPEGs - the burning question of the day!

[NutmegCT]

There seem to be two camps on this.

Most jpeg images are digitized files using a form of compression.

1. Opening and closing a jpeg image causes no degradation of the image.

2. Opening, editing, and saving a jpeg as a jpeg, causes degradation of the image, due to the compression. The more this happens, the more the image degrades.

What say ye all?

 

[JPSmit]

I say thou must have a lot of free time.

 

[NutmegCT]

Thou mayst say that ... but if someone is doing digital photography - like most of us - the comments from others may be helpful!

 

[Basil]

There seem to be two camps on this.

Most jpeg images are digitized files using a form of compression.

1. Opening and closing a jpeg image causes no degradation of the image.

2. Opening, editing, and saving a jpeg as a jpeg, causes degradation of the image, due to the compression. The more this happens, the more the image degrades.

What say ye all?

You are correct. Just opening and closing a JPEG will not cause any degradation, but editing will. The amount of degradation varies with what sort of editing you are doing. Cropping an image may cause slight degradation, but probably not noticeable unless the cropping is very severe. Changing things like brightness or tint, contrast, etc - things that affect the entire image, will cause more degradation because the entire image will need to be recompressed from scratch. The more you make these kinds of adjustments, the more the degradation will occur. Eventually you will start to see the degradation show up in the forum of pixel blocking, smearing, chunkiness, etc.

If I'm taking "snapshots" that I know I won't be editing much, maybe just to share on social media, I might sometimes shoot in JPG (or on the iPhone HEIC) but any time I'm doing any serious photography, I always shoot and edit in RAW (Canon Raw, but other lossless formats include TIFF, PNG, to name a couple). The HEIC format is similar to JPG but more efficient and sees less degradation than JPG, generally. This is a format that Apple uses (you can change the photo format to JPG on an iPhone if you want to, but why would you?)

For my serious photography, I always shoot RAW then edit in a non-destructive editing program (I use Lightroom but there are others). Then, when I have all the edits done, if needed I will export as a JPG.

 

[waltesefalcon]

I think of editing JPEGs as making a copy. Everytime you edit it it makes a new copy which is slightly less sharp, until you begin to lose definition.

 

[YakkoWarner]

Same thing applies to lossy audio/video compression - re-editing an MP3 or compressed video file requires uncompressing/editing/recompressing just like a photo. You can open and view/listen as often as you like, but any time you do something that requires an additional "save" at the end, you are creating a generational loss (just like copying from a cassette to cassette would be slightly worse each time). Uncompressed files you can manipulate all you like, but they are huge (especially in the video world).