Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and our Privacy Policy.
OK
Index  •   • New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Guest
New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Register to forums    Log in

 
FORUMS Community Talk, Chatter & Official Stuff AMASS Forum Software Talk 
Thread started 20 Jun 2017 (Tuesday) 18:37
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

Avoid recompressing small images?

 
sploo
premature adulation
2,265 posts
Gallery: 1 photo
Likes: 404
Joined Nov 2011
Location: West Yorkshire, UK
     
Jun 20, 2017 18:37 |  #1

From: https://photography-on-the.net …showthread.php?​p=18383016

Would it be possible for the forum software to avoid recompressing small (<=1280 pixels wide) JPEG images uploaded by users, where the file size is below some agreed level?

The example referenced above took a ~400KB file down to ~386KB, but at the expense of a fair bit of damage - which seems to me like the wrong decision in terms of storage space vs image quality.


Camera, some lenses, too little time, too little talent

  
  LOG IN TO REPLY
Pekka
El General Moderator
Avatar
17,548 posts
Gallery: 35 photos
Best ofs: 7
Likes: 1322
Joined Mar 2001
Location: Hellsinki, Finland
Post edited 11 months ago by Pekka. (2 edits in all)
     
Jun 27, 2017 14:35 |  #2

sploo wrote in post #18383081 (external link)
From: https://photography-on-the.net …showthread.php?​p=18383016

Would it be possible for the forum software to avoid recompressing small (<=1280 pixels wide) JPEG images uploaded by users, where the file size is below some agreed level?

The example referenced above took a ~400KB file down to ~386KB, but at the expense of a fair bit of damage - which seems to me like the wrong decision in terms of storage space vs image quality.

Thanks for the input.

See https://photography-on-the.net …showthread.php?​p=17983597 for a detailed explanation how we save uploaded images.

To not compress is not an option, even with small originals, sorry. 80% seems good for quality and loading speed. There is no point serving 400Kb+ images as there might be dozens on one thread page. Gallery pages in Flickr or GoDaddy are different type of page environments (one large image per page). Re-compression is also one form of security, as it "mangles" the original image bytedata.

I can of course see what can be improved the resize algorithms, and perhaps tune compression % with image size, but that is definitely something that does not happen in near future. The Robidoux settings are very good overall as the test photos in the post I liked to shows.

Also, all modern browsers do things to page's resized images, viewing the uploads at 100% (click the glasses) when browser zoom is at 100% is the only situation I make my decisions on.

And please note that all the above handles only images that are uploaded here, embedded photos are not touched in any way.


The Forum Boss, El General Moderator
AMASS 2.1 Changelog (installed here now)

  
  LOG IN TO REPLY
sploo
THREAD ­ STARTER
premature adulation
2,265 posts
Gallery: 1 photo
Likes: 404
Joined Nov 2011
Location: West Yorkshire, UK
     
Jun 28, 2017 05:21 |  #3

Pekka wrote in post #18388280 (external link)
Thanks for the input.

See https://photography-on-the.net …showthread.php?​p=17983597 for a detailed explanation how we save uploaded images.

To not compress is not an option, even with small originals, sorry. 80% seems good for quality and loading speed. There is no point serving 400Kb+ images as there might be dozens on one thread page. Gallery pages in Flickr or GoDaddy are different type of page environments (one large image per page). Re-compression is also one form of security, as it "mangles" the original image bytedata.

I can of course see what can be improved the resize algorithms, and perhaps tune compression % with image size, but that is definitely something that does not happen in near future. The Robidoux settings are very good overall as the test photos in the post I liked to shows.

Also, all modern browsers do things to page's resized images, viewing the uploads at 100% (click the glasses) when browser zoom is at 100% is the only situation I make my decisions on.

And please note that all the above handles only images that are uploaded here, embedded photos are not touched in any way.

Thanks - the security point is a good one.

The comparisons were made on the 100% views of the images. As you can probably see from my profile, I haven't uploaded many images myself ( :oops: ) but this wasn't the first time I've seen people comment that uploaded photos often show a clear reduction in quality.

That said - the few I have uploaded I've generally reduced in pixel width myself, and from the linked thread above it does seem to be the best compromise if uploading images (i.e. just recompressed by the forum, vs resized and recompressed).

I appreciate the timescale issue regarding looking at tuning the compression - every coding and testing job is trivial... when you're asking someone else to do it ;-)a


Camera, some lenses, too little time, too little talent

  
  LOG IN TO REPLY
Pekka
El General Moderator
Avatar
17,548 posts
Gallery: 35 photos
Best ofs: 7
Likes: 1322
Joined Mar 2001
Location: Hellsinki, Finland
Post edited 11 months ago by Pekka.
     
Jun 28, 2017 16:03 |  #4

sploo wrote in post #18388738 (external link)
Thanks - the security point is a good one.

The comparisons were made on the 100% views of the images. As you can probably see from my profile, I haven't uploaded many images myself ( :oops: ) but this wasn't the first time I've seen people comment that uploaded photos often show a clear reduction in quality.

If (any of) you have some clear examples of that problem, please PM me links to the originals and I'll get some test material.


The Forum Boss, El General Moderator
AMASS 2.1 Changelog (installed here now)

  
  LOG IN TO REPLY
sploo
THREAD ­ STARTER
premature adulation
2,265 posts
Gallery: 1 photo
Likes: 404
Joined Nov 2011
Location: West Yorkshire, UK
     
Jun 29, 2017 02:19 |  #5

Pekka wrote in post #18389186 (external link)
If (any of) you have some clear examples of that problem, please PM me links to the originals and I'll get some test material.

Pekka - see the images in https://photography-on-the.net …showthread.php?​p=18382720, and my original analysis in https://photography-on-the.net …showthread.php?​p=18383016

Image #3 in LJ3Jim's post is effectively an original (though 1280 pixels wide, but it could be used to compare against image #2 - which wasn't resized by the forum, but it was recompressed).

I'll PM LJ3Jim to see if he will send you the original, so the resize and recompression can be tested (i.e. the process that created image #1).


Camera, some lenses, too little time, too little talent

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)

989 views & 2 likes for this thread
Avoid recompressing small images?
FORUMS Community Talk, Chatter & Official Stuff AMASS Forum Software Talk 
AAA
x 1600
y 1600

Jump to forum...   •  Rules   •  Index   •  New posts   •  RTAT   •  'Best of'   •  Gallery   •  Gear   •  Reviews   •  Member list   •  Polls   •  Image rules   •  Search   •  Password reset

Not a member yet?
Register to forums
Registered members may log in to forums and access all the features: full search, image upload, follow forums, own gear list and ratings, likes, more forums, private messaging, thread follow, notifications, own gallery, all settings, view hosted photos, own reviews, see more and do more... and all is free. Don't be a stranger - register now and start posting!


COOKIES DISCLAIMER: This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and to our privacy policy.
Privacy policy and cookie usage info.


POWERED BY AMASS forum software 2.1forum software
version 2.1 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member is kiwix
826 guests, 356 members online
Simultaneous users record so far is 6430, that happened on Dec 03, 2017

Photography-on-the.net Digital Photography Forums is the website for photographers and all who love great photos, camera and post processing techniques, gear talk, discussion and sharing. Professionals, hobbyists, newbies and those who don't even own a camera -- all are welcome regardless of skill, favourite brand, gear, gender or age. Registering and usage is free.