jpg compression is better with low-detail pictures (if you take a 
picture of a piece of blank paper the same jpg-setting "Fine" gives a 
much higher compression ratio than say a picture of trees with lots of 
detail). The setting determines the amount of quality-loss you're 
willing to accept, not the resulting compression ratio.

Reinder


Smoothy wrote:
> Hey Tesselator,
> 
> Thanks for your reply.
> CP2100 has only two levels of compression at 1600*1200, which are Fine (1:4)
> and
> Normal (1:8).
> And yes, I took all of them at "Normal" setting.
> 
> About the building, now I understand.
> I think I expected a little too much of my camera!    ;)
> The bright sky at the top, sun behind the building, and...
> 
>>as if people were going not comming
> 
> Is it a movie or a still picture?!
> JK! You're right, and it was sunset, a cloudy sunset to be more specific.
> 
> Now if you don't mind, I can't understand something about these compressin
> ratios:
> The camera manual says that "Fine" is a 4:1 compression, well.
> But what this number has to do with the compression ratio I see in the image
> properties?
> Numbers like 15.7, 9.8, 10.0, ...
> The least compression I could get from my camera (1600*1200, Fine) was 7.4.
> But even with the quality set to Fine, different pictures taken with the
> camera, have different
> compression ratios shown in my image viewing software; something between 7.4
> and 10.0.
> What's the reason for this?
> 
> 
> Cheers.           :o)
> 
> --
> 
> 
> 
> "Tesselator" <jimmmboe@hotmail.com> wrote in message
> news:bbn68i$peu$1@catv02.starcat.ne.jp...
> 
>>"Smoothy" <bigvahid.antispam@hotmail.com> wrote in message
> 
> news:%czDa.11757$HG5.582599@news20.bellglobal.com...
> 
>>>You are right, I didn't know it's not allowed to post images in this
> 
> group.
> 
>>>I put all the pictures in this address:
>>>http://www3.sympatico.ca/vahid.afra/
>>>
>>>And again you are right, when saving the crop, the JPEG compression was
> 
> on
> 
>>>65%,
>>>I thought it is on 100%.
>>>But the pictures which are uploaded on the above address, are all
> 
> original.
> 
>>
>>If original then the camera compressed it.
>>
>>http://www3.sympatico.ca/vahid.afra/building.jpg is still 15.7 compression
>>ratio.  I believe the 2100 has 3 levels of JPEG and one level of
> 
> uncompressed.
> 
>>You had the setting on "Normal" right?  That's 15.7 jpeg.
>>
>>                                                                O :-)
>>
>>
>>
>>>Now I'd appreciate your comment about them.
>>>I myself think that all of them are grainy:
>>>Building Picture: the walls, ceiling, that parked car, ...
>>
>>I'd have to see an uncompressed version side by side to be sure
> 
> (impossible now)
> 
>>but as just a guess I'd say 70% of the noise you're seeing in that image
> 
> was
> 
>>introduced my the compression algorithm.  /I Think/ the other 30% or so is
> 
> due
> 
>>to the fact that you've maxed out the dynamic range of the CCD with that
> 
> particular
> 
>>exposure (err, picture).  See how the sky is looking over exposed yet the
> 
> areas
> 
>>under cars and even on the side of one car are underexposed?  That.
>>
>>I said "dynamic range of the CCD" and for this explaination that could
> 
> suffice
> 
>>even though the actual science is a little different.
>>
>>
>>
>>
>>>Falls Picture: the sky and water
>>>Flowers Picture: all over the picture I notice grains...
>>>Tree Picture: the leaves
>>
>>The noise you see in these shots is 99.5% due to jpeg compression error.
>>The 1200x1600x24 shots would be about 5.7megs if uncompressed and the
>>1024x768x24 shot of the flowers would be about 2.3 megs.
>>
>>
>>
>>
>>>I wonder why it should be like this, they are all taken in daylight, so
>>>there should be no effect like
>>>image noise (which usually noticable in night pictures with higher ISO).
>>>This camera (Nikon Coolpix 2100) IS SUPPOSED to have sharp and crisp
> 
> images!
> 
>>Yup I have a couple of coolpix too. They /are/ nice.  The shot you picked
>>there is one of the toughest to get right...  IF it can even be done.
>>The sun has set behind that building but is still illuminating the BG sky
>>and leaving the building face in the shadows.  Notice how the lamp-posts
>>are lit up?  I'ld say the camera did the best job possible under the
>>circumstances.  Ofcourse it /could/ be a sun-rise causing the same
> 
> condition
> 
>>but it looked to me as if people were going not comming so I assumed dusk.
>>
>>
>>
>>
>>>And thanks for your explanation about posting binaries.
>>>
>>
>>NP.
>>
>>        O :-)
> 
> 
>