PS7 – converting background of an old map

A
Posted By
AlanB
Feb 9, 2007
Views
480
Replies
6
Status
Closed
I have scans of several old maps, approx. 150 yrs old, and I would like to convert the backgrounds to white. Converting the image to bitmap with a 50% threshold works with some maps, but not those with a coloured background.

Can anyone suggest some simple techniques ?

A sample of one map is available at http://www.aqvh56.dsl.pipex.com/ originalmap.jpg

Thanks.
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B
beu
Feb 9, 2007
In article ,
AlanB wrote:
I have scans of several old maps, approx. 150 yrs old, and I would like to convert the backgrounds to white. Converting the image to bitmap with a 50% threshold works with some maps, but not those with a coloured background.

Can anyone suggest some simple techniques ?

A sample of one map is available at http://www.aqvh56.dsl.pipex.com/ originalmap.jpg

Thanks.

After first converting your originalmap.jpg to greyscale, your technique of converting the image to bitmap with a 50% threshold worked for me. I did darken the greyscale image a bit using levels in between.

Am I missing something? What is not working with maps that have a colored background?
G
granny
Feb 9, 2007
Can anyone suggest some simple techniques ?

A sample of one map is available at http://www.aqvh56.dsl.pipex.com/ originalmap.jpg

in PS7, I converted to Lab Color then used Levels with the black and white point selectors (used black pointer on black and white pointer on the gray background areas).. while still in Lab Color used unsharp mask then converted back to RGB Color mode.. sample from your map here: http://www.pixentral.com/show.php?picture=1BWNCZpO8j7ze1idSH BIr29AihV2

Also used Image/Adjustments/Replace Color (selecting the unwanted colors) and adjusting the lightness and fuzziness to suit.. then using unsharp in Lab Color

Both worked pretty well for me
—
"Granny"
R
ronviers
Feb 9, 2007
On Feb 9, 4:47 pm, "granny" wrote:
Can anyone suggest some simple techniques ?

A sample of one map is available athttp://www.aqvh56.dsl.pipex.com/ originalmap.jpg

in PS7, I converted to Lab Color then used Levels with the black and white point selectors (used black pointer on black and white pointer on the gray background areas).. while still in Lab Color used unsharp mask then converted back to RGB Color mode.. sample from your map here:http://www.pixentral.com/show.php?picture=1BWNCZpO8j7ze 1idSHBIr29AihV2

Also used Image/Adjustments/Replace Color (selecting the unwanted colors) and adjusting the lightness and fuzziness to suit.. then using unsharp in Lab Color

Both worked pretty well for me
—
"Granny"

Nice job. I still never think to get out of RGB.

Thanks for the tips,
Ron
A
AlanB
Feb 10, 2007
On 9 Feb, 22:03, (Bruce Uttley) wrote:
In article ,

After first converting your originalmap.jpg to greyscale, your technique of converting the image to bitmap with a 50% threshold worked for me. I did darken the greyscale image a bit using levels in between.

Am I missing something? What is not working with maps that have a colored background?

There is a noticable loss in quality using this method.
T
Tacit
Feb 10, 2007
In article ,
"AlanB" wrote:

I have scans of several old maps, approx. 150 yrs old, and I would like to convert the backgrounds to white. Converting the image to bitmap with a 50% threshold works with some maps, but not those with a coloured background.

Can anyone suggest some simple techniques ?

A sample of one map is available at http://www.aqvh56.dsl.pipex.com/ originalmap.jpg

Convert t image to grayscale and use Image->Adjust->Levels.

—
Photography, kink, polyamory, shareware, and more: all at http://www.xeromag.com/franklin.html
A
AlanB
Feb 10, 2007
On 9 Feb, 22:47, "granny" wrote:
Can anyone suggest some simple techniques ?

A sample of one map is available athttp://www.aqvh56.dsl.pipex.com/ originalmap.jpg

in PS7, I converted to Lab Color then used Levels with the black and white point selectors (used black pointer on black and white pointer on the gray background areas).. while still in Lab Color used unsharp mask then converted back to RGB Color mode.. sample from your map here:http://www.pixentral.com/show.php?picture=1BWNCZpO8j7ze 1idSHBIr29AihV2

Also used Image/Adjustments/Replace Color (selecting the unwanted colors) and adjusting the lightness and fuzziness to suit.. then using unsharp in Lab Color

Both worked pretty well for me
—
"Granny"

Thanks a lot.

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