Linked Questions

3
votes
2answers
760 views

How can I simulate JPEG quality degradation? [duplicate]

I am writing a report about file formats in images & their properties. In the report I want to talk about how file formats have lossy compression rather than lossless compression & I wanted to ...
25
votes
12answers
40k views

Does simply opening and closing a JPEG file decrease image quality?

I've had quite a few photography classes, read many photography books, and screened many forums. And I can't find a consistent answer to this question. One "camp" says there is a loss of image quality ...
10
votes
8answers
19k views

What is the “optimal” file size of JPEG images with respect to their dimensions?

I plan to write a script that will scan 100,000+ JPEG images and re-compress them if they are "too big" in terms of file size. Scripting is the easy part, but I am not sure how to categorize an image ...
5
votes
8answers
10k views

My mentor says to set image to Fine instead of RAW — how is this different from JPG?

So far, I have heard of one reason to have the camera save images as RAW instead of anything else. JPEG is a lossy form of image data and so I always thought it made sense to save the image data as is ...
7
votes
7answers
1k views

Is a JPG guaranteed to produce the same pixels?

I know there are plenty of benefits to shooting in RAW, but at the moment it seems that JPG works just fine for me. The file sizes are way smaller, and darktable seems to work just fine with them (...
8
votes
3answers
4k views

Does JPEG-to-JPEG export Lightroom reapply compression?

I want to crop a JPEG file in Lightroom and export that cropped file to another JPEG so that I can e-mail it. The exported JPEG should have the same quality as the original. I don't have the RAW file ...
11
votes
2answers
6k views

Is it worth using Pentax's Premium JPEG quality setting?

Similar: How do I choose which resolution (megapixel) and compression (normal, fine, superfine) to shoot in? The Pentax K-5 has a JPEG quality setting called "Premium", denoted by four stars, which ...
4
votes
4answers
27k views

What image quality is lost when re-saving a JPEG image in MS Paint?

Has anyone ever noticed that if you open a image in mspaint (.jpg, .jpeg) and then just save it, the image size is reduced by many folds. I use this method to reduce the file size. However, I am not ...
6
votes
2answers
6k views

Does converting image file formats affect quality?

Does converting image formats, such as from JPG to PNG, have any effect on image quality? I know converting from RAW to JPG has disadvantages, but what about other format conversions?
0
votes
2answers
5k views

GIMP Quality .jpg export - what is the best set up? [duplicate]

please could you tell what is the best common quality export value for .jpg image export in the GIMP? For example I set up the 100% for .jpg and for example for image 1,5 MB I will get the 5,2 MB or ...
3
votes
4answers
296 views

GIMP: Why can I set a higher quality than original image in the “Export Image as JPEG” dialog?

After having read the GIMP Export Image as JPEG section, I still have one understanding issue: Why am I able to select a higher quality value than the one from original image in the export dialog? For ...
0
votes
2answers
497 views

Trying to understand losses in jpg compression

I have a bunch of jpegs taken with a Nikon D3200 at 6016 x 4000. They weigh between 9M and 12M each. To try and reduce space a bit, I compressed copies with the default Windows utility, and the new ...
1
vote
2answers
231 views

Why does GIMP increase the size of exported JPEG files?

I'm using GIMP to edit some vacation pictures (JPEG files) taken with a rather old digital camera. Lacking a professional background, I just went about by trial and error and ended up adjusting the ...
2
votes
1answer
220 views

Why do some pictures rotated with exiftran have a vertical line on the right?

I use the following command in a script: exiftran -a -i mypic.jpg For some pictures, I get a wrong vertical offset, which is seen as a vertical line along the right border of rotated pictures. This ...
2
votes
1answer
67 views

Does compressing with chroma-subsampling multiple times degrade image quality?

Suppose I am creating a large image files out of smaller ones. The original images (jpeg) already have chroma-subsampling of 4:2:0. If one were to put them together and save again as a jpeg, would ...