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Compression problems

Iain Ashmore 

Member
Joined in January 2017
Posts: 2
Posted 19 March 2017 - 00:38 CET

It has been brought to my attention that when I am saving images in jpeg compression lines banding is being created, the issue I have here is that the original does not have this. The one on the left is the original and the one on the right is the jpeg compressed one.

How do I avoid this?

Attached photos:

Ray Abela 

Senior admin
Joined in July 2009
Posts: 328
Posted 19 March 2017 - 00:50 CET

Compression is a subject of over processing and harsh contrast.... always save your images to the highest jpeg quality number 12.

Igor Kmet 

Full member
Joined in September 2013
Posts: 73
Posted 19 March 2017 - 19:01 CET

Iain, first of all i see no sense in compressing original 1200x715 px , 340 k size JPEG picture to 1200x715px 176 k size, JPEG picture.

Commpression was applyed twice ( first probably in camera and second during compressing in SW). In AP is possible to upload 1200 ( max 1600 px) a 3 MB size without problems..other webs are similar with amount of data upload limitations.

You must understand that the bigger amount of px, the deeper compresion ( less kB ), and more fine structures in the picture always brings problems with quality of the picture. Compression in other words mean lost of information ( according to some algorhytmus).

I recommend you to use compression only once in the end of the postprocessing ( if necessary) and use maximum possible size in px and kB ( MB). In PS use command Save for web and quality 100. In the same moment check in left bootom corner if the amount of data ( kB or MB) is not to exceeding limit for website ( AP) ....

Iain Ashmore 

Member
Joined in January 2017
Posts: 2
Posted 19 March 2017 - 19:35 CET

Igor Kmet if I explain a bit about my habbits you may beable to pick up on something.

First I shoot in Raw always have done always will do.

I import into lightroom, do some basic edits level and remove dust spots if any.

I then work in photoshop where the first thing I do is size for my output so here I resize to 1260 pix usually.

I then work on the photo and export to web and save as a jpeg.

Thats basically it. So is there something I am doing wrong here?

Igor Kmet 

Full member
Joined in September 2013
Posts: 73
Posted 19 March 2017 - 22:56 CET

Iain, shooting in RAW is perfect , there is no compression, no loosing of info ( data) about each pixel in picture.

I would suggest you after exposure compensation in RAW ( if necessary ) to transform to TIFF .

Then all standart postprocessing do in TIFF only ( level,curves, shadow/highlights.....sharpening in the end and localy only -Layers in PS ).

Finaly resize to necessary pxs ( Bicubic for smooth gradients in PS ) and ( only onetime ) compress- with command Save for web ( maximum quality 100 ).

I am uploading to AP web mainly 1600 px pictures and size of the pictures ( depends how many fine structure are there) is in this case about 1 MB after compression ( Save for Web command).

The reason for TIFF picture editing ( in short) is that SW has maximum information to make changes in it and result is minimal degradation in quality.

Alexander Babashov 

Full member
Joined in June 2012
Posts: 19
Posted 1 April 2017 - 15:27 CET

The compression problem is primarily a problem of smooth gradients. JPG can not keep smooth gradients. First of all gradual gradients appear in the sky. In other areas, more abrupt transitions and more details mask possible problems

The RAW processing takes place in 16bit and there are no problems. The problem occurs when the saved in jpeg. Smooth gradients strongly contract because jpeg has only 8bit. Partial solution may be the addition of noise but in the sky noise can become another problem. Noise masks compression problems. I do not know the 100% way to solve the problem. It is always an attempt to find a balance in the right ratio of noise.

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