[TAG] Image size vs. file size

[Jimmy O'Regan]

On 29 September 2010 01:14, afsilva at gmail.com <afsilva at gmail.com> wrote:
>
>>
>> So... what makes an image - seemingly of the same type, according to
>> what "identify" is reporting - that much bigger? Does anybody here know?
>> And is there any way to make the file sizes closer without losing a
>> significant amount of visual content?
>
> It has to do with the compression of the image. I am going to guess someone
> else will have a scientific explanation, so I am not even going to bother...
> There is an interesting graph on wikipedia here:
> http://en.wikipedia.org/wiki/JPEG#JPEG_compression
>

On top of that, most digital cameras add a thumbnail of about 1/20th
of the file size, lots of cameras duplicate information in EXIF, IPTC,
and XMP (which is uncompressed XML), etc., but the compression - and,
as it's a lossy compression, the homogenisation of similar areas - it
the main factor.


-- 
<Leftmost> jimregan, that's because deep inside you, you are evil.
<Leftmost> Also not-so-deep inside you.