interesting problem about file size

I have a disk with lots of tiff images.  I run a script to rotate them all 
180 degrees.  For some reason, the files almost double in size after saving 
the rotated file.  Anybody know why this might be happening?

MKH

mkh wrote:
> 
> I have a disk with lots of tiff images.  I run a script to rotate them all
> 180 degrees.  For some reason, the files almost double in size after
saving
> the rotated file.  Anybody know why this might be happening?

Yes. The original files are LZW compressed but after opening
and rotating them you are saving the files as uncompressed TIFF.
In the File > Batch > Process dialog you use to run the script
against multiple files after setting TIFF as the Type in the
Save Options press the Options button and specify LZW Compression
for Compression and RGB for Color Channels. Since the LZW
compression is lossless the file size reduction is modest. Often
(and this depends on image content) the file size is about half
or a little less than the uncompressed file size for an 8 bit
per channel image. That accords with your observed approximate
doubling in size.

mkh wrote:
> I have a disk with lots of tiff images.  I run a script to rotate
> them all 180 degrees.  For some reason, the files almost double in
> size after saving the rotated file.  Anybody know why this might be
> happening?
> MKH

My first guess is that they where originally saved as LZW compressed Tiff 
and no longer are so Unless you told us just what your script does We can 
not tell what you did

-- 
Trev
You can always tell a Yorkshire man,
But you can't tell him much. 

thanks for the reply.  I tried to change to the lzw compression and the same 
thing is happening. File size is appx. double.
MKH

"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message 
news:47D1C4CB.B5780A01@agabatur.xednaps...
>
> mkh wrote:
>>
>> I have a disk with lots of tiff images.  I run a script to rotate them

>> all
>> 180 degrees.  For some reason, the files almost double in size after 
>> saving
>> the rotated file.  Anybody know why this might be happening?
>
> Yes. The original files are LZW compressed but after opening
> and rotating them you are saving the files as uncompressed TIFF.
> In the File > Batch > Process dialog you use to run the script
> against multiple files after setting TIFF as the Type in the
> Save Options press the Options button and specify LZW Compression
> for Compression and RGB for Color Channels. Since the LZW
> compression is lossless the file size reduction is modest. Often
> (and this depends on image content) the file size is about half
> or a little less than the uncompressed file size for an 8 bit
> per channel image. That accords with your observed approximate
> doubling in size.
> 

mkh wrote:
> 
> thanks for the reply.  I tried to change to the lzw compression and the
same
> thing is happening. File size is appx. double.

I don't think this is possible and so I suspect you are mistaken.
One difficulty of discussing this with you is that you are keeping
secret the exact steps you have been using. What you should be
doing is in File > Batch > Process setting TIFF as the Type in
the Save Options section of the dialog and then pressing the
Options button at which point a dialog appears where you can
set LZW compression. However, I don't know if you are doing this
or are erroneously attempting to set LZW compression in some
other dialog elsewhere in the program. For all I know you are
not relying on the batch processing capabilities of PSP and
instead you are trying to do your own file saving in your script,
in which case just about any outcome is possible depending on
the specifics of what you have in your script.

It should be easy enough to establish whether or not the TIFF
files are compressed. First start the PSP Browser and point it
to the folder containing the result TIFF files produced by your
script. Right click on the thumbnail for one of the TIFF files
in the browser and choose Information from the context menu
that appears. In the Info tab on the left read off what it says
for Compression in the Image Information section of the display.
Now navigate with the browser to the folder containing the
original TIFF files and repeat the right-click Information
command and see what compression the original files had.

When you rotate an image 180 degrees all you do is swap pixel
coordinates. In other words you don't change the image information
at all but you simply change the order in which it appears in the
image. This cannot possibly change the size of the image. The
only possibilities are (1) compressed images originally but not
after processing, (2) being mistaken about the file sizes, or
(3) thinkING you are rotating images 180 degrees but actually
doing something else (or at least something else besides rotation).
Since you haven't said anything about exactly what you are doing
this is as far as I can take the diagnosis.

> MKH
> 
> "Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in
message
> news:47D1C4CB.B5780A01@agabatur.xednaps...
> >
> > mkh wrote:
> >>
> >> I have a disk with lots of tiff images.  I run a script to rotate
them
> >> all
> >> 180 degrees.  For some reason, the files almost double in size
after
> >> saving
> >> the rotated file.  Anybody know why this might be happening?
> >
> > Yes. The original files are LZW compressed but after opening
> > and rotating them you are saving the files as uncompressed TIFF.
> > In the File > Batch > Process dialog you use to run the script
> > against multiple files after setting TIFF as the Type in the
> > Save Options press the Options button and specify LZW Compression
> > for Compression and RGB for Color Channels. Since the LZW
> > compression is lossless the file size reduction is modest. Often
> > (and this depends on image content) the file size is about half
> > or a little less than the uncompressed file size for an 8 bit
> > per channel image. That accords with your observed approximate
> > doubling in size.
> >