lossless compression of still images - recommendations?

Joel Rees joel.rees at gmail.com
Mon Feb 20 10:14:36 UTC 2017


On Mon, Feb 20, 2017 at 7:14 AM, Robert Heller <heller at deepsoft.com> wrote:
> At Sun, 19 Feb 2017 18:40:49 +0000 (UTC) "Ubuntu user technical support,  not for general discussions" <ubuntu-users at lists.ubuntu.com> wrote:
>
>>
>> On Sun, 19 Feb 2017 13:26:48 -0500 (EST), Robert Heller wrote:
>> >
>>
>> > If the OP wants truely lossless compression, he is not going to be
>> > using JPEG.  JPEG is *lossy* compression.  He should be using PNG
>> > instead.
>>
>> Of course, you are correct.  I meant to go back and edit that --- then
>> forgot.
>>
>> But, my comment remains:  No two, seperately taken, identical images
>> should result in an identical bit stream, or large sub-sets of the bit
>> stream.  But, perhaps, this is the second time I've ever been wrong.  :-)
>
> It might depend on the equipment taking the picture and the nature of the
> scene. If it is an *artifical* scene with very carefully controlled lighting,
> etc. it might be possible. But yes, with almost any natrual scene with natrual
> lighting, it is likely impossible for there to be any possibility of near
> identical scenes to have anything like even remotely similar bit streams.
>
> What the OP might be able to do is do some sort of image processing and use
> some sort of statistical analysis to extract the "near-identical" parts of the
> images and remove them (or replace them with some sort of "not interesting"
> mask).  Basically a pre-processing step to cause the *saved* data set to only
> have the "small" parts where something interesting is happening and tossing
> the larger parts that are logically "unchanging" (and thus uninteresting).

In other words, do part of what jpeg compression does, by hand.

It won't be lossless, of course.

On the other hand, it might be possible to tune the loss in acceptable
ways. Manual lossy compression. Interesting thought.

>>
>> Jonesy
>>
>>
>
> --
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-- 
Joel Rees

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http://joel-rees-economics.blogspot.com/2017/01/soc500-00-00-toc.html
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