[sdiy] OK, one of you computer geeks, explain this..

[Peter Forrest]

Of course it's an anomaly, though - a bit like my insurance company wanting 
to charge me more for third-party liability, fire and theft than for fully 
comprehensive cover which includes all that **and** damage to my own 
car......
This is of course on-topic because I use the car for ferrying synths around 
practically every week.
OK, it's not on topic.  I shut up.
Peter

----- Original Message ----- 
From: "James R. Coplin" <moog at qwest.net>
To: "'J. Larry Hendry'" <jlarryh at iquest.net>; "'Synth-DIY'" 
<synth-diy at dropmix.xs4all.nl>
Sent: Monday, January 31, 2005 5:26 AM
Subject: RE: [sdiy] OK, one of you computer geeks, explain this..


> It would depend on the format used for the colorspace.  A bmp format is 
> raw
> and even if it is grey scale but the color space is specified as 24bit, 
> each
> pixel will be 24 bits even if they only store the 8 bits of data that make
> up greyscale.  If you were to convert the greyscale to zillions of colors
> via 24bit jpg, then the color space compression will give you the gains.
>
> All of this is dependent on the application you are using for the 
> scanning,
> how the pdf translator deals with the info, etc.
>
> James R. Coplin
> ***************
> If anyone asks of my whereabouts,
> simply tell them i've gone out the window
> for a spot of tea and am not
> expected back any time soon.
> ***************
>
>> -----Original Message-----
>> From: owner-synth-diy at dropmix.xs4all.nl [mailto:owner-synth-
>> diy at dropmix.xs4all.nl] On Behalf Of J. Larry Hendry
>> Sent: Sunday, January 30, 2005 5:37 PM
>> To: Synth-DIY
>> Subject: [sdiy] OK, one of you computer geeks, explain this..
>>
>> While this pertains to scanning and file structure, it is not off topic
>> because I am scanning synth schematics.  Due to the black and white
>> scanning
>> I have done in the past, I pretty much understand how to minimize PDF 
>> file
>> size for a given resolution (through the BMP file).  However, I am now
>> working on documents that require color and grayscale. While some of the
>> document is color, about 2/3 is grayscale.  So, I thought I would save
>> file
>> size by scanning those in gray instead of color.
>>
>> Here is what puzzles me. Let me throw some file sizes out there for one 
>> of
>> my large 11x17 pages to see if any of this makes sense.
>>
>> This page was scanned (paste a few together) in grayscale as a bitmap and
>> results in 13.2 MB file size.  I normally scan everything to Bitmap and
>> then
>> convert to PDF as that has always given me the most efficient file size
>> (past B&W experience).  So, I convert the file to a PDF and the resulting
>> file is about 2.6 MB.  Well, I was hoping for better, but I thought that
>> was
>> it.  Then, I started noticing some of the color pages were smaller once
>> converted to PDF.  I wondered why since the color BMP files were so much
>> larger.  So, as an experiment, I took my 13.2 MB grayscale page and
>> converted it to full 16 million colors file in my photo editor.  As
>> expected, the file size jumper up to 39.7 MB.  I'm still understanding OK
>> up
>> to here.  But, now I take that color file and convert it to PDF.  The
>> resulting file is only 1.15 MB.
>>
>> So in summary,
>> gray file started 13.2 MB bitmap
>> converted to PDF @ 2.6 MB
>>
>> same gray file to full color = 39.7 MB
>> converted that color file to PDF @ 1.15 MB
>>
>> Of course, since the original source file was grayscale, even the color
>> PDF
>> looks grayscale.  In fact I cannot tell the two images apart.  However,
>> the
>> one that was converted to the very large color file first ended up the
>> MUCH
>> smaller file size when converted to PDF.
>>
>> If any of you who are considerable more geeked than I concerning 
>> computers
>> can 'splain this to me and Lucy, that would be great.  Maybe I will learn
>> something that will help me additionally control the file size on these
>> large, highly detailed scans.
>>
>> Larry Hendry
>> computer geek NOT.
>> :-)
>>
>>
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