>That wouldn't help as different programs use different scales in their
>Options or Save As boxes to determine JPEG compression levels, there
>doesn't seem to be a standard.
>
>Also as other people in this thread have pointed out, even repeatedly
>saving the file at the same compression level i
ver, your point is well taken.
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Derek Clarke
> Sent: Tuesday, April 03, 2001 12:04 PM
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Subject: RE: filmscanners: File format
>
I asked our webmaster to replace the converted files with the files I sent
him.
Jack
-Original Message-
From: Bill Ross [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, April 03, 2001 4:33 PM
To: [EMAIL PROTECTED]
Subject: RE: filmscanners: File format
I just ran some experiments and
It seems the algorithm rather rapidly reaches the point of "no further
benefit" and stabilizes the file size, and likely also the amount of
change in the pixel structure.
Yes, perhaps with variations of degree between programs. Until
a lower-quality rating is sel
te and caused everyone to go to all this experimental trouble
testing out their positions. :-)
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Arthur Entlich
Sent: Tuesday, April 03, 2001 3:16 AM
To: [EMAIL PROTECTED]
Subject: Re: filmscanners: File for
Hey, Bill... your webmaster also made those files password protected
Mike M.
Bill Ross wrote:
> I just ran some experiments and
> I put the images into a directory on our website:
> http://www.asf.com/temp/. Our webmaster helped out by converting all the
> ti
Without wishing to add to you "pain" ;-), I was surprised to determine
that this exact situation (the "leveling" of the compression) occurs
much sooner than I expected. You will probably have noted that via my
recent posting to that effect, where I monitored file sizes after
repeated Jpeg co
I decided to put my money where my mouth is ;-) and I just took an
image, which mainly consisted of some color areas and some typeface, and
ran it through Photoshop's jpeging. With one set, I used level 4 and
the other set I applied level 2. In each case, I did a series of ten
jpegs applicat
I just ran some experiments and
I put the images into a directory on our website:
http://www.asf.com/temp/. Our webmaster helped out by converting all the
tifs to jpegs for viewing (uh-oh). I've asked him to convert them back,
The converted-back ones will be just a
Derek wrote:
>The difficult part is re-saving the file with the same compression ratio as
it had originally.
>Even the mighty Photoshop just uses one compression ratio for all JPEG file
saves.
You can save at the same compression ratio, but that doesn't mean much. I
noticed this several months a
> Your results will vary depending on the image you use. I hope this data is
> useful. Your conclusions will vary depending on your needs obviously.
>
I did a similar test using a 1k by 1k piece out of the PhotoDisc test image.
The original image is extremely sharp and contains nice flesh tones a
PM
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Subject: RE: filmscanners: File format
The difficult part is re-saving the file with the same compression ratio
as it had originally.
Even the mighty Photoshop just uses one compression ratio for all JPEG
file saves. That compression ratio can be set man
I've been holding off weighing in on this subject area because I'm not
expert but I may be able to shed some light. I just ran some experiments and
I put the images into a directory on our website:
http://www.asf.com/temp/. Our webmaster helped out by converting all the
tifs to jpegs for viewing (
r to resaving the file should not result in any additional losses
> in
> data or quality.
>
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Larry Berman
> Sent: Thursday, March 29, 2001 8:31 PM
> To: [EMAIL PROTECTED]
> Subjec
--- You wrote:
Anyway, I just know I'm going to be nit-picked to death about my very
simplified descriptions to what are very complex mathematical functions,
but I hope this is somewhat helpful in explaining the differences
between JPEG and other compression methods, and why a photograph shows
On Mon, 2 Apr 2001 14:37:09 +0100 Alan Tyson
([EMAIL PROTECTED]) wrote:
> Is it perhaps that jpeg is specially suited to
> 'photographic' images, and not to areas of single solid
> colours with sharp edges like Henk's image? The latter is
> rare in photographic images, and lossless gif does an
On Mon, 2 Apr 2001 14:44:57 +0300 (EET DST) =?ISO-8859-1?Q?Hugo_G=E4vert?=
([EMAIL PROTECTED]) wrote:
> > Tony Sleep wrote:
> > >If you merely open and save a JPEG at the same compression,
> > >without editing, you lose nothing
> > With my small and simple test I found other results :-)
>
> Co
The only very slight disagreement I'd have is that it might be possible
that if you open and save in JPEG format enough times, you might
actually reach a point where you are "chasing your tail" and that
certain random pixels will change one way one time and then
hat sort of thing anyway.
>
> Would someone who understands the maths of jpeg compression
> care to comment and suggest reasons for the discrepancy,
> please?
>
> Or maybe Henk's and my results need repeating, like cold
> fusion and life on Mars?
>
> Alan T
>
>
I have to agree with Hugo here. His explanation is what I always read
and learned, and it also makes perfect sense.
The only very slight disagreement I'd have is that it might be possible
that if you open and save in JPEG format enough times, you might
actually reach a point where you are "ch
TED]>
Sent: Monday, April 02, 2001 12:44 PM
Subject: Re: filmscanners: File format
Come on guys, what happens when you save with jpeg or any
other
compression that loses data? You save the file, the
compression algorithm
desides what information can be thrown away, and then saves
it..
On Fri, 30 Mar 2001, Henk de Jong wrote:
> Laurie Solemon wrote:
> > Out of curiosity, how many timed did you do this and what sorts of
> > changes did you see?
>
> I took a picture, saved, closed and re-opened it ten times.
> After every step (save, close and re-open) I compared the new image w
//
Thank you for every one who participate my question.
Now I got the point.
HT Tin 31st/Mar/2001
//
Tony Sleep wrote:
>
> On Fri, 30 Mar 2001 09:49:05 +0800 httin ([EMAIL PROTECTED]) wrote:
>
> >
> > Did any one knows whether is there any informations/details loses when
> > store in compres
Laurie Solemon wrote:
> Out of curiosity, how many timed did you do this and what sorts of
> changes did you see?
I took a picture, saved, closed and re-opened it ten times.
After every step (save, close and re-open) I compared the new image with the
original and found small differences, we all k
Friday, March 30, 2001 10:58 AM
To: [EMAIL PROTECTED]
Subject: Re: filmscanners: File format
Tony wrote:
>If you merely open and save a JPEG at the same compression, without
editing, you lose nothing. If you edit, you lose information. It's
impossible to quantify how much, since it varies de
mon <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, March 30, 2001 5:51 PM
Subject: RE: filmscanners: File format
> Out of curiosity, how many timed did you do this and what
sorts of changes
> did you see? Have you tried the same experiment using
another image editing
rent package's jpeg save
routine, because each has its own scale and criteria for
'jpeg quality'.
Regards,
Alan T
- Original Message -
From: Lynn Allen <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, March 30, 2001 5:57 PM
Subject: Re: filmscanners: File format
e--
From: [EMAIL PROTECTED] (Tony Sleep)
To: [EMAIL PROTECTED]
Sent: March 30, 2001 1:40:00 PM GMT
Subject: Re: filmscanners: File format
On Fri, 30 Mar 2001 09:49:05 +0800 httin ([EMAIL PROTECTED]) wrote:
>
> Did any one knows whether is there any informations/details loses when
>
?
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Henk de Jong
Sent: Friday, March 30, 2001 12:59 AM
To: [EMAIL PROTECTED]
Subject: Re: filmscanners: File format
> >Each time there would be some generational loss.
>
> Not necessarily true. If you open an
PROTECTED]
Subject: RE: filmscanners: File format
Mikael wrote:
>I think there are some myths about jpg. tif. psd. and high quality printing
pictures.
We (printing company, myself and a medical company picture bank)
have done tests about saving pictures that later can used to print out on
high
Allen" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, March 30, 2001 4:08 PM
Subject: RE: filmscanners: File format
> Mikael wrote:
>
> >I think there are some myths about jpg. tif. psd. and high quality
printing
> pictures.
> We (printing comp
Thank you - I must have joined soon after that discussion.
Maris
- Original Message -
From: "Alan Tyson" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, March 30, 2001 4:29 AM
Subject: Re: filmscanners: File format
| Maris said:
|
| > Just a not
Mikael wrote:
>I think there are some myths about jpg. tif. psd. and high quality printing
pictures.
We (printing company, myself and a medical company picture bank)
have done tests about saving pictures that later can used to print out on
high glossy paper.
All files are scanned in 350 ppi
We
On Fri, 30 Mar 2001 09:49:05 +0800 httin ([EMAIL PROTECTED]) wrote:
>
> Did any one knows whether is there any informations/details loses when
> store in compressed JPG format in maximum quality 10 and while you keep
> opening and saving the same file many times?
If you merely open and save a
? that we photographers are "over do it " when we are
delivering pictures in big tif or psd files.
Mikael Risedal
Lund
Sweden
>From: "Laurie Solomon" <[EMAIL PROTECTED]>
>Reply-To: [EMAIL PROTECTED]
>To: <[EMAIL PROTECTED]>
>Subject: RE: filmscan
Maris said:
> Just a note on LZW compressed image portability - I have
run into one
> instance where an LZW compressed image was not portable -
when exporting a
> 48-bit compressed TIFF from Vuescan to Corel PhotoPaint 9
it opens but the
> image is unrecognizable. If exported uncompressed there
> >Each time there would be some generational loss.
>
> Not necessarily true. If you open and close ( or resave) the compressed
file
> without changing the compression from one quality level to another in the
> case of .jog or without resampling the image prior to closing or resaving
> the file, t
once in PhotoPaint it can be compressed using LZW. This appears to be one
exception.
Maris
- Original Message -
From: "Rob Geraghty" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, March 29, 2001 10:15 PM
Subject: Re: filmscanners: File format
| larry wr
To: [EMAIL PROTECTED]
> Subject: RE: filmscanners: File format
>
>
> >Each time there would be some generational loss.
>
> Not necessarily true. If you open and close ( or resave) the
> compressed file
> without changing the compression from one quality level to another
Hi Rob,
The original question was asked about repeatedly opening and saving as a jpeg.
>larry wrote:
> > What would be the point of storing and reopening and saving
> > the same image in a compressed format repeatedly. Each time
> > there would be some generational loss.
>
>Rob wrote: This is o
nal losses in
data or quality.
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Larry Berman
Sent: Thursday, March 29, 2001 8:31 PM
To: [EMAIL PROTECTED]
Subject: Re: filmscanners: File format
What would be the point of storing and reopening and saving the s
Only if you change the quality when resaving the .jpg file or if you
resample the file in any way prior to resaving the .jpg file even at the
same quality level. With .tif files, you will lose information only if you
resample the file after opening it and before resaving it.
-Original Messag
larry wrote:
> What would be the point of storing and reopening and saving
> the same image in a compressed format repeatedly. Each time
> there would be some generational loss.
This is only true of lossy compressed formats like jpeg and PCD.
> Store in an uncompressed native format to your grap
What would be the point of storing and reopening and saving the same image
in a compressed format repeatedly. Each time there would be some
generational loss. Store in an uncompressed native format to your graphics
program. If you open a jpeg in Photoshop it automatically takes on the
characte
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