Can I make gifs print as clearly as pdfs do on my LJIIIp?

  • Thread starter Thread starter Alan Douglas
  • Start date Start date
A

Alan Douglas

Hi,
Just curious: pdf line art prints beautifully on my LaserJet IIIp,
but drawings in other formats are converted to bitmaps at 300 dpi and
they look terrible. How does pdf do it? Does this mean my IIIp has
postscript capability?

I've done newsgroup and google searches but finding the right
keywords is difficult.

If it matters, I'm running Windows 3.11and of course an equally
ancient version of Acrobat Reader (3.01).

Thanks, Alan
 
Alan Douglas said:
Hi,
Just curious: pdf line art prints beautifully on my LaserJet IIIp,
but drawings in other formats are converted to bitmaps at 300 dpi and
they look terrible. How does pdf do it? Does this mean my IIIp has
postscript capability?

I've done newsgroup and google searches but finding the right
keywords is difficult.

If it matters, I'm running Windows 3.11and of course an equally
ancient version of Acrobat Reader (3.01).
Click to expand...


The IIIp doesn't have PostScript. Even if it did you'd have to be
using a PostScript printer driver, which you would know if you were.

The LJIII is a 300dpi printer, so so Acrobat is printing at 300 dpi
too. Acrobat is just good at printing, it was noticeably better than
Ghostscript, even just text, when I was printing on an LJIII.

I suspect that when you print images they are being scaled up; a 300
dpi image printed at 100% should be the optimum. You might look at the
printer settings, for dithering etc. Also the printer's "RET" setting.

If you're printing colour images, you might convert them to greyscale
before printing (don't save the converted form if you want to keep the
colour). Photoshop or other paint programs should do a better job of
that than leaving it to the printer driver.
 
Just curious: pdf line art prints beautifully on my LaserJet IIIp,
Alan replied:
The IIIp doesn't have PostScript. Even if it did you'd have to be
using a PostScript printer driver, which you would know if you were.

The LJIII is a 300dpi printer, so so Acrobat is printing at 300 dpi
too. Acrobat is just good at printing, it was noticeably better than
Ghostscript, even just text, when I was printing on an LJIII.
Click to expand...

Thanks for the response. I thought I read somewhere that there was
a Postscript cartridge or card available for the LJIII.

It's just frustrating: I can print a schematic or chart from
Acrobat and all the lines are sharp, but in a gif schematic printed
through Paint Shop Pro, the lines are rows of dots.

Regards, Alan
 
Thanks for the response. I thought I read somewhere that there was
a Postscript cartridge or card available for the LJIII.
Click to expand...

Yes, there were PS cartridges that used the font cartridge slot, with
driver software that were made by the likes of HP and Pacific Data at
least.
It's just frustrating: I can print a schematic or chart from
Acrobat and all the lines are sharp, but in a gif schematic printed
through Paint Shop Pro, the lines are rows of dots.
Click to expand...

It all depends upon the source images themselves. Line art or vector images
are resolution independent mathematical representations of an image. As
such they can be scaled to any size and the resulting output is only
limited by the resolution of the output device.

Bitmaps on the other hand are simply pixel by pixel representations of the
image and are limited in resolution to the number of pixels in the original
source image. While it is possible to resample and interpolate bitmaps to
increase there size, you ca not increase the amount of information present.

This is not to say you can not get good quality images from bitmaps, it
just high resolution source material. A brute force rule of thumb is
approximately 300 pixels per inch in the output.
 
Ed Ruf replied:
Bitmaps on the other hand are simply pixel by pixel representations of the
image and are limited in resolution to the number of pixels in the original
source image. While it is possible to resample and interpolate bitmaps to
increase their size, you can not increase the amount of information present.
Click to expand...

I have to admit, the original gif isn't as sharp as it appears on
the monitor: if I blow it up in Paint Shop, some of the lines are one
pixel wide but may are two, and some of the text isn't even readable.
This is the original I'm working with at present:

http://antiqueradios.com/photogallery/LR8N3PSq.gif

However it still looks a whole lot better than the LJIII image: the
single-pixel-width lines have serrated edges when printed.

So presumably the gif bitmap has more pixels than the LJIII can
handle, resulting in resampling at 300 dpi?

Thanks, Alan
 
I have to admit, the original gif isn't as sharp as it appears on
the monitor: if I blow it up in Paint Shop, some of the lines are one
pixel wide but may are two, and some of the text isn't even readable.
This is the original I'm working with at present:

http://antiqueradios.com/photogallery/LR8N3PSq.gif
Click to expand...

This is only 827 x 640 pixels, not a lot to work with.
However it still looks a whole lot better than the LJIII image: the
single-pixel-width lines have serrated edges when printed.
Click to expand...

How are you printing in PSP? What version? When you view on the screen in
PSP, it is resampling the image to display on the screen unless you are
viewing it at 100%
So presumably the gif bitmap has more pixels than the LJIII can
handle, resulting in resampling at 300 dpi?
Click to expand...

No it's the other way around, you have too few pixels in the image to
print. Since the image has no dpi setting in the file it will use what ever
you have set the default to in PSP. (File => Preferences => General Program
Preferences => Unit's => Default resolution). Pixels mean one thing dpi
another. For a general discussion see http://www.scantips.com/basics01.html
and http://www.scantips.com/basics03.html

If you print at 300 ppi without resampling the image (interpolating) then
you'll end up with an ~2-3/4 x 2 " print. This would map one pixel in the
image to one dot laid down by the printer. This is pretty much as good a
print as you can get. You can resize and resample using bicubic to get a
larger printer with maybe slightly more readable text. But given the
poorness of the original image, you can do much with it.
 
Ed Ruf replied:
How are you printing in PSP? What version? When you view on the screen in
PSP, it is resampling the image to display on the screen unless you are
viewing it at 100%
Click to expand...

It's 3.0 (Windows 3.11). Thanks for the clarification, which is a
lot more than I found in an hour of google searches. This will make
some sense when I've had time to digest it and try some experiments.

Regards, Alan
 
Alan Douglas said:
Thanks for the response. I thought I read somewhere that there was
a Postscript cartridge or card available for the LJIII.
Click to expand...

There are -- in fact I have one for the III, but it wouldn't work in
the IIIp and you would need to be using a PS driver in any case,
otherwise the printer will just use native PCL. But it wouldn't help
this.
It's just frustrating: I can print a schematic or chart from
Acrobat and all the lines are sharp, but in a gif schematic printed
through Paint Shop Pro, the lines are rows of dots.
Click to expand...

The difference isn't in how it's printed, but that the GIF is a
screen-res bitmap.
This is the original I'm working with at present:
http://antiqueradios.com/photogallery/LR8N3PSq.gif
Click to expand...

This image is 827x 640 pixels.
If printed at 100% size at 300 dpi, it will be 2.75" x 2.13".
Anything larger than that and you will get the staircasing and other
artifacts you mention.
So presumably the gif bitmap has more pixels than the LJIII can
handle, resulting in resampling at 300 dpi?
Click to expand...

No, the opposite. Dots are being interpolated. Also, the image is
anti-aliased -- meaning it uses shades of grey to give a higher visual
resolution -- which works on screen but not in print, as lasers use
just wider spaced dots for greys rather than grey dots (which you
can't get in a b/w printer). So smooth grey transitions become abrupt
rough dots.

If you really must work with this image, first convert to TIFF and
then make it greyscale. GIF has a lot of limitations and is optimised
for low res video images. But if at all possible, go back to the
original file and output lineart, such as PS, and convert that to PDF.
Otherwise redraw it; I think it would probably be faster than trying
to filter it to sharpen and otherwise mess with it in PhotoShop or
whatever.
 
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