Re: [MLUG] Followup on WebCam.

[vapor <EMAIL:PROTECTED>]

Truely lossless refers to the fact that it can be decompressed and still 
have all of the information.  At the point in time in which it is a 
lossless jpeg, though, it merely has information that can be translated 
with a little work into a lossless image.  It is lossless in that it 
can, eventually, be a picture with no missing information.  At the point 
in time in which it is a jpeg, however, it is still drawn using the jpeg 
grids and as a result does not appear as a lossless image.  It has 
nothing to do with hardware.. it should merely be used as a way to save 
a larger image in half the space to be decompressed at a later time back 
into the larger-sized image.

Zach

Christian M. Cepel wrote:

> Zack and Mark.. Thanks for the replys... Here's the thing I don't 
> understand.  This happens even when no compression is applied.  Like 
> you say, it's not using a true lossless format.  What I'm wondering 
> is... Why?  I've taken snapshots using the software that came with the 
> camera, and I get the same thing.  Could the Hardware be doing this?  
> I wouldn't think anybody would develop a hardware/driver interface 
> that would intentionally throw out data it's already captured.  Very 
> odd.  Very frustrating.
>
> If I had my way, I'd use my Kodak DC4800, but Kodak saw fit to flip 
> the bird at their customers had has refused for the past 3 years to 
> allow method of accessing the camera other than their vile 'easy 
> share' software.  People are begging for Twain, or similar.  Kodak 
> could care less.
>
> It's driving me crazy.  I keep messing with the focus, 'cause I keep 
> thinking I can improve the crispness.
>
> //Christian
>
> vapor wrote:
>
>> It is a result of the jpeg.  Unfortunately, there is no one standard 
>> for lossless jpeg... there's 3 different standards if I recall 
>> correctly, and the ISO standard is the only one that is truely 
>> lossless.  Even so, to get lossless out of the image you need to 
>> decompress it back into a truely lossless format (not jpeg).  The ISO 
>> standard only works well with smoothly-changing-in-tone images and 
>> still typically compresses the shown image by 2:1, which I would 
>> guess is what is happening as "HamsterCam.jpg" is only 77k.  There's 
>> no real point to having a lossless jpeg as you still need to 
>> decompress it to utilize the data available.
>>
>> Regards,
>> Zach
>>
>> Christian M. Cepel wrote:
>>
>>> http://HamsterCam.bramblethorne.org/
>>>
>>> Its been live for about a week, and underwent the normal few days of 
>>> shakedown for any new gadget.  Its proving popular with the 'hamster 
>>> community' :)
>>>
>>> Hardware:
>>> Ended up getting a Logitech Messenger IM cam.  Not really happy with 
>>> it, but considering I bought the $20 off brand and then had to 
>>> return it and came home with something with true 640x480 CMOS 30fps, 
>>> I guess I didn't do too badly.  The one thing I cannot figure out is 
>>> why if it takes at 640x480 CMOS TRUE, why I'm seeing macropixeling 
>>> in an uncompressed image.  Here's the thing.  I would expect 640x480 
>>> distinct pixels, but I do not expect them to be grouped  and aliased 
>>> into little blocks of 64 pixels, 8 per side.  Here's what I mean.
>>>
>>> http://hamstercam.bramblethorne.org/HamsterCam-Macropixel.jpg
>>>
>>> Anyone know why this is?  I'm considering trying a webcam in linux 
>>> just to see if its something other than hardware.
>>>
>>> Wife doesn't want to leave the machine in Linux all the time so was 
>>> forced to find Windoze software to drive it.  Ended up using 
>>> Active.  Fairly happy with it except that it won't do incremental 
>>> numbers on the FTP setup with the oldest being deleted, keeping only 
>>> the newest X shots.  Came with a slim little Java applet that I will 
>>> keep even if I switch software later on.  Would be happier if it (or 
>>> the camera hardware) would allow 90deg rotation instead of just 180, 
>>> and if one could set multiple events of the same type (multiple FTP 
>>> destinations/tasks).
>>>
>>> Anyways...
>>
>>
>>
>>
>>
>> _______________________________________________
>> members mailing list
>> EMAIL:PROTECTED
>> http://mlug.missouri.edu/mailman/listinfo/members
>
>
>
>


_______________________________________________
members mailing list
EMAIL:PROTECTED
http://mlug.missouri.edu/mailman/listinfo/members