change/compress picture resolution to 600 dpi?

PowerPoint 2003 on WinXP

I did google before posting, and found lots of hits on exporting powerpoint
as an image, the descriptions of the built-in picture compression
options,...but not what I'm looking for.

I have two powerpoints with some pre-cropped high-resolution pictures. Total
filesize is about 50MB, the other is 75MB.

I want to use [format picture/ picture/compress] to reduce my filesize if
possible. However, the presentation is designed for printed use (not an
on-screen presentation), and the pictures need to be extremely clear when
printed (resolution matching the printer's 600dpi output).

Is there a registry setting where I can change the compress setting from
200dpi up to 600dpi? I don't care if the dialogue box changes, as long as
the resolution isn't pushed below 600.

I'd rather stay with huge files than have lower than 600dpi resolution, so
if there isn't a solution, I'll still be ok unless the printer chokes on
such a large file (maybe requiring printing a page or two at a time).

Thank you!
Keith

I want to use [format picture/ picture/compress] to reduce my filesize if
possible. However, the presentation is designed for printed use (not an
on-screen presentation), and the pictures need to be extremely clear when
printed (resolution matching the printer's 600dpi output).

Is there a registry setting where I can change the compress setting from
200dpi up to 600dpi? I don't care if the dialogue box changes, as long as
the resolution isn't pushed below 600.

You probably don't need 600dpi images.

Let me make a couple educated guesses:

- You're working with color or grayscale images, not pure b/w 1-bit images
- You have a b/w laser printer rather than a color printer, probably a
PostScript based printer.

If both guesses are true, you definitely don't need 600dpi.

Laser printers can't print gray; they can print black dots or not print black
dots. By changing the way they print black dots, they can *fake* grayscale
values but in doing that, they trade away resolution for the ability to produce
so-called "halftones" (gray values). It's too complicated to go into here but
the net result is that for a typical 600dpi laser printer, anything over about
150dpi is wasted, so PPT's 200dpi "Print" compression setting should do fine.

But don't trust me. Test on your own equipment.

Make three copies of one image with different filenames.

Add three slides to a typical presentation you'd create.

Pop one image into PPT normally (Insert, Picture from File)

Pop another in and let PPT compress it to 200dpi (print setting)

Externally downsample the third to 600dpi and then Insert, Picture, From File
to bring it into PPT.

Now print all three slides.
Let truth be revealed. ;-)

If the results are surprising in any way, c'mon back and let's talk.



I'd rather stay with huge files than have lower than 600dpi resolution, so
if there isn't a solution, I'll still be ok unless the printer chokes on
such a large file (maybe requiring printing a page or two at a time).

Thank you!
Keith


-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================

Hi Steve!

I am working with color images; I'm using a networked color laser printer
that is at least 600dpi (it may be 1200, but I'm not positive). I assume the
difference between 600 and 1200 would be beyond the scope of human
detection. I'd think (just a guess, I haven't tested) that the difference
between 100-200 is more easily detectable, and the difference between
200-300 detectable under certain circumstances, etc.

I hadn't thought about it, but the color laser probably must also use
interpolated dots to provide the appearance of the color range- so the more
color, the lower the 'true' resolution would be anyway. I can't help but
wonder if a 100dpi color image on a 300dpi printer is rendered in a way to
use the extra pixels for the coloring- probably not, it probably just prints
larger blocks of interpolated color... man, now I'm going to be wondering
about that all weekend. I suppose a color inkjet could overprint (resulting
in dye mixing for color rendering), but that's a whole different animal
anyway.

The good news (although with your logic, probably irrelevant) is that I
realized I could print these to pdf at 600dpi, effectively downsizing the
file. Of course, I have no idea what else the conversion might be doing to
the images (compression, etc). At least in initial tests, it seems to print
with sufficient clarity for our needs, and the file dropped from 30MB to
about 2MB- a heck of an improvement either way.

Thanks again for the logical explanation - next time I won't worry so much!
Keith

"Steve Rindsberg" wrote in message
...

Let me make a couple educated guesses:

- You're working with color or grayscale images, not pure b/w 1-bit images
- You have a b/w laser printer rather than a color printer, probably a
PostScript based printer.

If both guesses are true, you definitely don't need 600dpi.

Laser printers can't print gray; they can print black dots or not print
black
dots. By changing the way they print black dots, they can *fake*
grayscale
values but in doing that, they trade away resolution for the ability to
produce
so-called "halftones" (gray values). It's too complicated to go into here
but
the net result is that for a typical 600dpi laser printer, anything over
about
150dpi is wasted, so PPT's 200dpi "Print" compression setting should do
fine.

But don't trust me. Test on your own equipment.

Make three copies of one image with different filenames.

Add three slides to a typical presentation you'd create.

Pop one image into PPT normally (Insert, Picture from File)

Pop another in and let PPT compress it to 200dpi (print setting)

Externally downsample the third to 600dpi and then Insert, Picture, From
File
to bring it into PPT.

Now print all three slides.
Let truth be revealed. ;-)

If the results are surprising in any way, c'mon back and let's talk.



I'd rather stay with huge files than have lower than 600dpi resolution,
so
if there isn't a solution, I'll still be ok unless the printer chokes on
such a large file (maybe requiring printing a page or two at a time).

Thank you!
Keith


-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================

I am working with color images; I'm using a networked color laser printer
that is at least 600dpi (it may be 1200, but I'm not positive). I assume the
difference between 600 and 1200 would be beyond the scope of human
detection.

Not sure about color lasers, but with B/W laser printers, the diff's visible
(especially when it comes to halftones, since you have twice the resolution to
trade off in exchange for gray tones).

I'd think (just a guess, I haven't tested) that the difference
between 100-200 is more easily detectable, and the difference between
200-300 detectable under certain circumstances, etc.

The images? Yes, I'd think so, because at 100 - 200 you're starting below and
going past the point where the printer's throwing away data it can't use. From
200-300 you're starting past that point and continuing further in the same
direction.

I hadn't thought about it, but the color laser probably must also use
interpolated dots to provide the appearance of the color range- so the more
color, the lower the 'true' resolution would be anyway. I can't help but
wonder if a 100dpi color image on a 300dpi printer is rendered in a way to
use the extra pixels for the coloring- probably not, it probably just prints
larger blocks of interpolated color... man, now I'm going to be wondering
about that all weekend. I suppose a color inkjet could overprint (resulting
in dye mixing for color rendering), but that's a whole different animal
anyway.

We're on the same page here. g

The good news (although with your logic, probably irrelevant) is that I
realized I could print these to pdf at 600dpi, effectively downsizing the
file. Of course, I have no idea what else the conversion might be doing to
the images (compression, etc). At least in initial tests, it seems to print
with sufficient clarity for our needs, and the file dropped from 30MB to
about 2MB- a heck of an improvement either way.

The PDF results will depend on your PDF driver settings (JPG vs TIFF
compression, the amount of JPG compression applied, stuff like that). And
since it gives you quite a bit of control over what happens in the end, going
to PDF is a pretty good solution. I like this page.

Thanks again for the logical explanation - next time I won't worry so much!

Nah, go ahead and worry if it triggers such pleasant exchanges.


Keith

"Steve Rindsberg" wrote in message
...

Let me make a couple educated guesses:

- You're working with color or grayscale images, not pure b/w 1-bit images
- You have a b/w laser printer rather than a color printer, probably a
PostScript based printer.

If both guesses are true, you definitely don't need 600dpi.

Laser printers can't print gray; they can print black dots or not print
black
dots. By changing the way they print black dots, they can *fake*
grayscale
values but in doing that, they trade away resolution for the ability to
produce
so-called "halftones" (gray values). It's too complicated to go into here
but
the net result is that for a typical 600dpi laser printer, anything over
about
150dpi is wasted, so PPT's 200dpi "Print" compression setting should do
fine.

But don't trust me. Test on your own equipment.

Make three copies of one image with different filenames.

Add three slides to a typical presentation you'd create.

Pop one image into PPT normally (Insert, Picture from File)

Pop another in and let PPT compress it to 200dpi (print setting)

Externally downsample the third to 600dpi and then Insert, Picture, From
File
to bring it into PPT.

Now print all three slides.
Let truth be revealed. ;-)

If the results are surprising in any way, c'mon back and let's talk.



I'd rather stay with huge files than have lower than 600dpi resolution,
so
if there isn't a solution, I'll still be ok unless the printer chokes on
such a large file (maybe requiring printing a page or two at a time).

Thank you!
Keith


-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================




-----------------------------------------
Steve Rindsberg, PPT MVP
PPT FAQ: www.pptfaq.com
PPTools: www.pptools.com
================================================