Photo and amount of compression

[Burgerman]

I will soon delete these. All of these 5 photos are the exact SAME picture. All are full resolution 47 megapixel images. Thats around 8250 x 5000. So are huge.
The only difference between them all is the file size. JPG files are compressed. The difference here is the amount of compression.

The 1st is the lowest quality, very small 900k file with very high compression. View at 50% or 100% and look above the left hand can at the background to see the result of this high level of compression. Ignore focus, only the top edge of can 1 is in focus here!
https://www.wheelchairdriver.com/doomed ... 0.85MB.jpg
See the block colours, the banding and paterns this compression causes? This is because its a tiny fle size from a massive image.

This is no 2. Also compressed. But less so. It is the same image. But now its 1.1MB.
https://www.wheelchairdriver.com/doomed ... y1.1MB.jpg
Its less extreme but still shows the same effect but reduced a little. Good enough for the web.

This is 3. It is medium compression. It results in a 2.23MB file. Its good enough for most purposes. And now is starting to be a bigger file.
https://www.wheelchairdriver.com/doomed ... 2.23MB.jpg

This is no 4. It has low compresion, but still much smaller than the original file. This is now 4.6MB.
It shows low levels of blocking or banding of colours. Good enough for practically anything.
https://www.wheelchairdriver.com/doomed ... y4.6MB.jpg

Best jpg quality. So can be used for anything incuding billboard sized prints etc. This isnt as good as a 250MB tiff file. But is close unless you really closely examine it. A big photo file.
https://www.wheelchairdriver.com/doomed ... ty34MB.jpg

But even better colours and smoother gradations and less "spottyness" and even less blocking affect or colour banding can be had from a TIFF file generated from the lossless raw image. But this is some 240MB per image and too big to post here.

.jpg files are a compromise. They must be. Especially on the internet. Only you can decide what quality you need and how much compression to apply.

[slomobile]

Only you can decide what quality you need and how much compression to apply.

Not when the forum you upload photos to has a strict 300kb limit.

[Burgerman]

That limit is fine for normal sized images. The comparison wasnt meant for the forum.
The ones I linked to are straight from camera 47 MegaPixels, 8.450k wide. Fine to print an 8 foot wide photo. And thats only 900k.

I will upload a sensibly large one at 300k or less at good quality soon...

[Burgerman]

270K and its big enough at 100% to hang a poster on your wall.

If you resized this to half, it would be just 75K and still too big for the screen.

[slomobile]

I agree its a sensible size for the forum. Just wish there were a dead simple non interactive automatic way to point the forum at an image file of any size on my computer and have the forum only take the 300kb it wants.

[Burgerman]

Well if you have a pc it takes a few seconds to compress or resize to suit the purpose you have in mind. All levels of compression are great for different things. All sizes from original 45mp raw at 100MB or edited tiff file at 200MB down to a thumnail have their place. How does a forum know what you intend or want?
For e.g graphics or text look terrible compressed. In that case you would choose to use a gif file instead as its limited in colous but uncompressed and super clear even if small in file size. It all depends on your intent. I cant allow more than 300k per picture as this forum is already 10GB plus. And hosting gets expensive! And most of that is images.

The picture above is some 2000 pixels wide, and compressed as much as I can without noticibly damaging quality at this size. It is a small 225kb and better than most of the images on here. It just takes a human eye to decide on adequate size, adequate quality versus file size. Just 225K...

This, view at 100% is the whole point of the post. https://www.wheelchairdriver.com/board/ ... &mode=view
To show that with an ounce of effort you can post good images and still be way under the 300k limit.

The idea was to show exactly what the various compression levels do. And show how good it can be without being megabytes in size if you bother to optimise it.

[slomobile]

I finally had to buy a windows PC again to run Roborun, but had been getting by with phone and chromebook.

Shrinking an image usually involved transfering from phone to chromebook, uploading the image to a website, manually cropping and selecting a resolution at random to see what size it comes out to. Repeat several times on original till it is small enough. Then download the result. Upload that to the forum.

The result I always want for here is <300k .jpg
It is a constant regardless of the source image. The original framing is what I want. But I crop over and over anyway to reduce size without hurting image quality. It is the manual iteration without knowing file size till the very end that becomes annoying.
Seems there ought to be a way to select a maximum file size and have the tool just show the rescaled result at that file size to see if the quality is acceptable, or if the original needs to be recropped manually, then auto rescaled again.

The intermediate attempts fill up storage and chromebook reclaims freed space very slowly, keeping a copy of deleted files in "recents" which user does not have control over. Usually running out of storage on the chromebook or phone during the process. Often not having a USB cable for the transfer, a dying battery on one or the other, lost internet connection, or not being able to read the small text on the phone.

[Burgerman]

Coral paint shop pro tells you image size as you adjust the compression before saving.
I think photoshop does too.
I also tend to shoot raw anyway so use DXO PhotoLab which means shoting at numbers like 64,000 iso (not 6400) is as clean as 100 iso... That too tells you what image quality/size etc when saving.

So I resize, then save at the compression/file size I want from a high quality raw/tiff file. All in all takes about 10 secs. But for DXO at least you need a workflow, understanding of what you are doing and about 32 cpu cores... It murders the Graphics/CPU when saving using its AI noise reduction. Takes about 6 mins to save 1 image on a laptop! About 15 secs on a super powerful PC with a 3090 graphics card. So its not ideal for phone pics!

So corals Paint Shop Pro is probably easiest and best. All are free of course.

Space isnt an issue. SSDs are cheap today. Even my laptop has a fast Lexar 4TB NVMe drive. And a spare drive. And a removable 4TB NVMe for backups and spare boot drive. Its a good job. My camera makes 70MB raw files, 200+MB tiffs and jpgs any size you choose.

[slomobile]

Space isnt an issue.

Try using a 16GB or 32GB Chromebook for any length of time and say that. That isn't RAM size, that is soldered on SSD size, not upgradable.

[LROBBINS]

Now that you have a Windows PC, there are many options. I use IrfanView X64 for most image manipulation. It is rather "manual" - more menu driven than GUI (but certainly less work than using a smart phone or chromebook). It has all the bells and whistles for cropping, re-sizing, sharpening, compression etc. and imports and exports to multiple file types - including multi page PDF and videos (remember to install the Plugins to have the full list), or create slide shows. It is legally free, and doesn't use much space nor processor action.

[HiltonP]

FastStone is also pretty good..... lightweight, powerful, versatile, stable, and free!

[Burgerman]

Free?
Everything is free. And especially all the best software. Its just a matter of knowing where, how, and which is best!

Try using a 16GB or 32GB Chromebook for any length of time and say that. That isn't RAM size, that is soldered on SSD size, not upgradable.

Thats why I dont.
Those things are owned by an advertising marketing and tracking company. And I have 32GB RAM in my latop and 128GB in my desktop PC! As for storage, I have 2 4TB fast SSDs in my laptop, and 2x 2TB as well as 2x 4TB in my desktop PC. And at least 2/3rds of it is already used.

If you want any expensive software, free, with cracks and fixes, including Windows LTSC, or office, photoshop, etc let me know!

Hell my camera has 2x 1TB memory cards!

[martin007]

"Legally free."

[Burgerman]

That just means that its usually (but not always) junk. Or at least very basic. Or has nags to buy upgraded versions, or ads, etc.
Theres a reason things like photoshop or premier, ms office, DXOlabs etc are industry standard tools. And a reason they cost a fortune... Well if you pay.