Help! How do I convert RGB jpegs to monochrome bitmap tifs

RB
Posted By
robin_booth
Apr 12, 2004
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1758
Replies
11
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Closed
In photoshop 6.0 on windows 2000 — need to convert black and white line art images that are currently RGB jpegs into monochrome bitmap tifs.

Please describe the steps required.

Thanks so much.

RB
Related Tags
bitmap conversion help how rgb tiff

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L
LenHewitt
Apr 12, 2004
Image>Mode>Greyscale
Image>Mode>Bitmap
Save As
JS
John_Slate
Apr 12, 2004
….and make sure you have a bare minimum of 600ppi at final printed size.

Upsampling while in grayscale mode will yield a better result than simply increasing the ppi during the conversion to bitmap mode.
GA
George_Austin
Apr 12, 2004
"…and make sure you have a bare minimum of 600ppi at final printed size…"

John,

Could you elaborate on the reason for this seemingly excessive print resolution?

George
L
LenHewitt
Apr 12, 2004
George,

We’re back to ‘printing solids’ <g>

A bi-level bitmap has no antialiasing, and no screening will be applied at print time. It therefore should ideally be at the printer resolution for best quality, just as is printing rasterized text.
GA
George_Austin
Apr 13, 2004
Len,

Then,I guess in this case, "monochrome" means "monotone"—no grays, just B&W—no dithering—a printer dot is a pixel—ppi=dpi??

George
RW
Rene_Walling
Apr 13, 2004
a printer dot is a pixel—ppi=dpi

In this case, yes
L
LenHewitt
Apr 13, 2004
George,

I guess in this case, "monochrome" means "monotone"<<

That’s what the original poster said:

"convert black and white LINE ART images … into monochrome BITMAP tifs."
GM
Glenn_Mitchell
Apr 13, 2004
Don’t use Image:Mode:Grayscale. There are better ways of generating a high contrast grayscale image from a color RGB image.

My digital darkroom has a lot of resources on B&W conversion.

Tutorials
<http://www.thelightsright.com/DigitalDarkroom/Tutorials.htm>

Learning Gallery
< http://www.thelightsright.com/DigitalDarkroom/LearningGaller ies.htm>

PS Action Set
< http://www.thelightsright.com/DigitalDarkroom/PhotoshopTools .htm>

To save a TIFF instead of a JPEG, just select the TIFF file type in the Save As dialog.

You should not necessarily save at 600 ppi or higher. The optimal setting will depend on your printer. Select too high a setting, and you’ll soften the image unnecessarily.

I use a RIP called ImagePrint for my B&W fine art prints. I use 380 dpi, because IP will resample to 380 if I do not. I have never resampled higher than 380 dpi, and I get extremelely fine B&W prints with fine art papers like Arches Infinity and Crane Museo.

Cheers,

Mitch
RW
Rene_Walling
Apr 13, 2004
You should not necessarily save at 600 ppi or higher. The optimal setting will depend on your printer.

It is necessary.

Mitch, you are thinking greyscale mode, we are talking bitmap mode. Two entirely different beasts
GM
Glenn_Mitchell
Apr 13, 2004
Had I paid attention to the reference to line art, I would have picked up in the fact we were talking about bitmap files with just a binary bitmap. 😉

Cheers,

Mitch
GH
Gernot_Hoffmann
Apr 13, 2004
The OP should tell the people here whether he is talking about Photoshop Bitmap (halftoning)
or
General Bitmap (ordinary raster image, like Windows BMP or TIFF).

PhS Bitmap is a rare application. The halftoning is normally done by an imagesetter RIP.
If the OP REALLY wants to apply halftoning by PhS then he should give a little more information about the intended para- meters (Lpi, dpi, angle, pattern).

Best regards –Gernot Hoffmann

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