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Open - Better compression for Images - Issue #352


Thordelan

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Hello,

 

First of all, pardon my English, I'll try my best to make it clear.

 

I've been spending a lot of hours the last few days to reupload Super NES Boxes (fronts and backs), why ?

Because most of them are between 1,5mo and 5mo, sometimes even more...I thought that was way too much space wasted (I haven't checked other systems yet but I bet there will be more of those) so I tried to recompress them and for the exact same quality and size, I get images between 300ko and 800ko, that's a lot of gained space (or rather a lot of space wasted for everyone at the moment if we don't do anything about it).

Let's say you have 1000 SNES games, that's easily 3go wasted, only for the SNES and for the boxes (if you count 1 front and 1 back, but there are usually more with the different regions).

 

So here is my (noob) question/suggestion : would it be possible to implement a kind of script that would recompress images when you upload them ?

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Hi @Thordelan, to be honest I believe we should be valuing quality over disk space with the LaunchBox Games Database. Even if it *appears* that there is no quality loss when recompressing images, there always is. I prefer that we not recompress existing images in the LaunchBox Games Database for this reason. These days both hard drive space and bandwidth are plentiful, so I would prefer to keep as large of images as possible, in their original form.

In the future we could provide an option to download compressed images, but I would not want to alter the originals.

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The problem with most of the files that are 500>5000 Kbyte in size, especially screenshots, is that the actual quality doesn't even justify for a size of 100 Kbyte, because those are mostly upscaled 320x240 pictures which look pretty hideous.

I used Irfan-view to rescale and compress all files over 500 Kbyte and cold shrink my collection from 12 Gb down to 2 Gb without any visible degradation. Game screenshots should be limited to the system's original resolution, unless they are treated with an hires CRT filter.

 

Edited by Wutex
typo
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On 02/09/2016 at 0:19 AM, Special T said:

Let me know what you think. By the way, does XnConvert shrink the size of png files without losing quality?

I have no idea yet , only used it for *.jpg untill now :)

Since I've been making a lot of changes in my collection the last few days, I will download again most of the medias later, then compare both programs to know which does the better job for shrinking *.png :)

 

Anyway, back to the subject, this is getting insane in my opinion : http://gamesdb.launchbox-app.com/games/images/27804

Almost 10mb for a single 1528*2100 picture, and that's not the only one...I don't know...

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I think compressing a PNG is fine as it's loseless. I have noticed resaving existing PNG's in Photoshop tends to shrink them down. However JPEGs I would leave alone if at all possible. While it might be difficult to see lowering the quality of a JPEG, it can and usually does if you have a picky eye.

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That being said at least Thordelan may have a point. With Photoshop I can't tell a difference between saying JPEG's at quality level 10 vs 12. And the file size savings is significant. I submitted a few NES boxes to show what I mean. If we want to stick with the highest quality by all means, but I can't tell a difference at anything 10 or above. Below that however I can, can anybody else see a quality difference?

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I typically don't convert everything to png unless it makes sense for example, I've tried to convert several jpg images into png's but they tend to be larger in size so no reason to convert them. However, bmp files which some emulators use when capturing screen shots compress very well when converting to png and can be reduced in size by 50-75%... at least on the tests I've done using Sega Genesis & 32x images.

Anyway, I ran some tests this morning to see which program is better PNGGauntlet or XnConvert. I didn't have any bmp image files to test so I just used png images I found on my hard drive.

========== Test #1 ==========

I used 107 different png screenshots taken of Shining Force III for Sega Saturn and ran them through each program.

PNGGauntlet Tested Using Default Settings
- Time: 20 Minutes
- File Size: reduced in size by 1,531,904 bytes (Original: 15,978,496 bytes - Compressed: 14,446,592 bytes)

XnConvert Tested Using Minimum Compression (level 1)
- Time: 6 Seconds
- File Size: the files actually increased in size by 3,678,208 bytes (Original: 15,978,496 bytes - Compressed: 19,656,704 bytes)

XnConvert Tested Using Maximum Compression (level 9)
- Time: 60 Seconds
- File Size: the files actually increased in size by 364,544 bytes (Original: 15,978,496 bytes - Compressed: 16,343,040 bytes)

========== Test #2 ==========

I tried another test using 96 different png screenshots taken of various Sega 32X games and ran them through each program.

PNGGauntlet Tested Using Default Settings
- Time: 8 Minutes
- File Size: reduced in size by 573,440 bytes (Original: 8,130,560 bytes - Compressed: 7,557,120 bytes)

XnConvert Tested using minimum compression (level 9)
- Time: 18 Seconds
- File Size: the files actually increased in size by 450,560 bytes (Original: 8,130,560 bytes - Compressed: 8,581,120 bytes)

========== Conclusion ==========

XnConvert Pros: Extremely easy to use (drag & drop), allows for batch conversions between various image formats, & fast

XnConvert Cons: Doesn't appear to reduce file size or compress png images

PNGGauntlet Pros:  Extremely easy to use (drag & drop) and won't increase file size i.e. it will either reduce file size of that image or leave it in it's original format if converting increases file size

PNGGauntlet Cons: Since it tests several different compression algorithms it takes a long time to compress images (even longer if the image is extremely large i.e. several MB in size like cover images)

So, XnConvert is an extremely easy to use however it doesn't compress png files to save space as far as I can tell. On the other-hand, PNGGauntlet does take a lot longer to process images, however it will either reduce the file size in the conversion process of skip that image if converting results in a larger file. So, for my needs, PNGGauntlet takes the gold. On a personal note, since PNGGauntlet uses a lot of the computer resources, I will normally just leave my computer on over night and start the compression process when I go to bed, by the time I wake up it's done and I saved save and didn't have to waste any time configuring anything because the default settings are already set to maximum compression.

========== Suggestions to LaunchBox Developers ==========

My suggestion would either be to ask people to use PNGGauntlet before uploading images or possible run the images through the program on the back end once they've been uploaded to the website. Maybe add a flag (somewhere behind the scenes) indicating whether or not the image has been optimized. Yes, the file size reduction is marginal, however it you extrapolate that over hundreds of thousands of images and hundreds of thousands of downloads, I would assume the reduced load on the server would be worth it plus the images would only need to be optimized once and then after that everyone benefits.

Combining the two examples above would equate out to a savings of approximately 10371.15 bytes per image (2,105,344 bytes / 203 images). I don't know how many images are on this site but lets say the database contains 100,000 images (100,000 x 10371.15) which would equate out to a total savings of about 1 GB. The trade off seems worth it to me since the reduction in file size doesn't degrade the image quality.

Thoughts?

Edited by Special T
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14 hours ago, hubz said:

That being said at least Thordelan may have a point. With Photoshop I can't tell a difference between saying JPEG's at quality level 10 vs 12. And the file size savings is significant. I submitted a few NES boxes to show what I mean. If we want to stick with the highest quality by all means, but I can't tell a difference at anything 10 or above. Below that however I can, can anybody else see a quality difference?

 

That's exactly my point but I didn't want to argue since @Jason Carr made it clear.

But you are right, there is the point the human eye doesn't see the difference anymore, or need a few seconds to see a very subtle difference. I wish I could show my compressed 500kb images next to the 3mb original and ask people to tell fast which one has the bigger size...

 

 

13 hours ago, RetroArcade said:

Ehhh tested out my MAME wheel art last night, 6000+ images and would have saved a few mere MBs. Haven't tested a set of images that would be larger in size to see if it would do much. This was with PNGgauntlet

Well, wheels are already very small (not above 400px 99% most of time since they are all from HyperSpin) and thus don't take much space. The real "problem" is all those huge covers, fanarts, flyers, etc. A huge amount of space could be saved whether they are jpg or png for no (significant) difference at the end (in my opinion).

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I PNG gauntlet and it greatly reduced the size of my file due to a large number of bump files present but truthfully if I ran it for 20 minutes and it only reduced my file size by 1.5 megabytes than I would have to say that it isn't worth using in that scenario. So unless you have a huge amount of bump files that it will greatly reduce the size of I wouldn't bother.

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