Gene Heskett wrote:
> On Tuesday 08 July 2003 10:26, schnatte@xxxxxxx wrote:
>
>>> schnatte@xxxxxxx wrote:
>>>> Matlab supportes JPEG. But I want work with JPEG while to my
>>>> knowledge JPEG is compressed. Normal I want to work with bmp
>>>> but I heared it ist better with ppm. This is why I want to work
>>>> with it. Perhaps its false.
>>>
>>> I dont want to be rude, but your English is very hard to
>>> understand (although it is probably much better than my German!)
>>> It seemed you did *not* want JPEG *because* it is compressed.
>>> Right?
>>>
>>> If so, *why*? Non-compressed formats (or even expanded, if you
>>> use ascii) will exacerbate bandwidth problems. You must have a
>>> pretty good reason to reject compressed formats, but we still
>>> dont know what it is.
>>
>> Sorry for my english I know it, I will try to work on it.
>
>
> Its quite adequate for me. And thousands of times better than my
> comprehension of your native tongue. All the german I ever knew I
> got from translating 50 year old Telefunken schematics, which is now
> not very much, no recent refreshers.
>
>
>> For me a compressed image format is a format that have losses. e.g.
>> I take 5*5 pixels and calcul the mean of it. So the size is smaller
>> as further. In the normal status you dont see the quality losses
>> but if you zoom in. Do you understand, what I mean with compressed?
>> OK but after I had saved the images I want to analyse it with
>> Matlab. And I've been afraid that if I use compressed images which
>> had information losses, the results are wrong. That's all.
>
>
> An entirely valid reason to avoid any lossy image format.
>
Absolutely. But then the first thing to avoid is to go through YUV420P
(which uses only 1.5 bits of info per pixel) or even through any other
pixel format than the one that will be used for the image processing in
Matlab.
So, the specs are: 25fps (BTW at what size and for how long a time), a
lossless codec, which has to be acceptable to MATLAB, and no lossy
colorspace conversions. Thus JPEG is out (lossy), and XPM too (uses a
colormap). That leaves BMP and maybe GIF (does a TrueColr GIF exist?),
and maybe PGM and PPM - I dont know much about them, are they really
lossless *and* free of colorspace conversions?
--
Michel Bardiaux
Peaktime Belgium S.A. Bd. du Souverain, 191 B-1160 Bruxelles
Tel : +32 2 790.29.41
