threshold level between black and white when changing imag..

[Dima]

Archived from groups: rec.photo.digital (More info?)

Hello
How to change a threshold level between black and white when changing
image type to monochrome using "threshold" "Halftone" "Custom" mode in
MS Photo
Editor or in any other image editor?
I want to convert a grayscale black and white drawing to a monochrome
1bit image. Since I do not know how to change a threshold level between
black and white, the monochrome 1bit image results too light, some
details are disappeared.

 

[Dima]

Archived from groups: rec.photo.digital (More info?)

MS Office PhotoEditor names a "line drawing" "monochrome 1 bit" in an
image properties.

 

[Guest]

Archived from groups: rec.photo.digital (More info?)

When I have tried this I find I usually have to play with the contrast
and brightness controls a lot BEFORE I convert to the one-bit mode. I
also sometimes have to use a filter that washes out variations
spatially across the image.

 

[Guest]

Archived from groups: rec.photo.digital (More info?)

Dima wrote:
> Hello
> How to change a threshold level between black and white when changing
> image type to monochrome using "threshold" "Halftone" "Custom" mode in
> MS Photo
> Editor or in any other image editor?
> I want to convert a grayscale black and white drawing to a monochrome
> 1bit image. Since I do not know how to change a threshold level between
> black and white, the monochrome 1bit image results too light, some
> details are disappeared.
>
It would seem to me that you are trying to convert a grayscalt to a line
drawing. I would try the find edges function then go about dropping the
unwanted tones and place emphasis on the edges. There is really no such
thing as a monochrome 1 bit image, other than that of a line drawing.

 

[Guest]

Archived from groups: rec.photo.digital (More info?)

Jack-of-the-Dust wrote:

> There is really no such thing as a monochrome 1 bit image, other
> than that of a line drawing.

www.google.com: image dithering

http://www.dca.fee.unicamp.br/dipcourse/html-dip/c3/s7/front-page.html
http://www.webstyleguide.com/graphics/dither.html
....

 

[Paul]

Archived from groups: rec.photo.digital (More info?)

Dima wrote:

> Hello
> How to change a threshold level between black and white when changing
> image type to monochrome using "threshold" "Halftone" "Custom" mode in
> MS Photo
> Editor or in any other image editor?
> I want to convert a grayscale black and white drawing to a monochrome
> 1bit image. Since I do not know how to change a threshold level between
> black and white, the monochrome 1bit image results too light, some
> details are disappeared.


If you really want to do this it requires resampling to a huge output
file size & will be a slow memory intensive operation. You should be
asked what resolution to output, chose a higher number like 600dpi or
more. It won't be readable on a computer monitor until you zoom in 100%.
This is for making something that will xerox well or for making a
silkscreen print. It will use either lines or dots to represent the shades.