WakeTurbulence From United States of America, joined Apr 2004, 1291 posts, RR: 17 Posted (7 years 10 months 1 week 2 days 18 hours ago) and read 2319 times:
I recently had 2 shots rejected for compression only. My question is how can a file that is 1100-1200 pixels wide and less than 1MB, saved at 12 (Maximum) in Photoshop be compressed? Also, how can you tell if a shot is compressed, does the overall quality go down? Another thought I had was that this was with a new lens. I don't think it has anything to do with this matter, but it is a thought. Just curious on what some people think. Thanks.
WakeTurbulence From United States of America, joined Apr 2004, 1291 posts, RR: 17 Reply 2, posted (7 years 10 months 1 week 2 days 14 hours ago) and read 2276 times:
Glad to get smiles out of you Jeff. When I edit my images I don't save more than once. If I see a problem after saving I will go back and re-edit. Thanks for the tips though. I'll have to go back to the edits and take a closer look to see what's up. Thanks again.
StealthZ From Australia, joined Feb 2005, 5547 posts, RR: 47 Reply 4, posted (7 years 10 months 1 week 2 days 14 hours ago) and read 2267 times:
An uncompressed 8 bit TIFF file of 1200x800 is 2.75Mb so any JPG file of less than a Mb has significant compression.
Do you shoot RAW? If you are shooting JPG there is already significant compression applied. eg a JPG out of my Canon 10D of a typical aviation scene may be 1.5-2.5Mb that same shot uncompresses to an 18Mb TIFF file.
So careful management of compression and image versions is required to minimise degradation.
If your camera sends text messages, that could explain why your photos are rubbish!
WakeTurbulence From United States of America, joined Apr 2004, 1291 posts, RR: 17 Reply 5, posted (7 years 10 months 1 week 2 days 13 hours ago) and read 2262 times:
First to Harry, I am pretty sure my camera isn't compressing the files any differently than it has been the last year or so, good thought though. Next to Chris, sorry for the confusion, I was talking about edited files. My original JPG's are between 1.5Mb and 3.5Mb. I shoot JPG for convenience, but I probably should learn about RAW. After 250+ photos on Anet with JPEG I don't see myself switching anytime soon, but it might be good to experiment with and see. Thanks for the thoughts guys.
Martin21 From Netherlands, joined Aug 2001, 347 posts, RR: 1 Reply 6, posted (7 years 10 months 1 week 2 days 8 hours ago) and read 2248 times:
Quoting JeffM (Reply 1): If work was done and saved as .jpg repeatedly, you will have compression each time it is saved.
This is not entirely true. This only happens when opening, saving and closing the photo and opening, saving, closing and so on. When you open a JPG photo you can edit and save it as many times as you want without losing quality. I know for sure, just tested it with photoshop.