On Sat, 17 Aug 2013 14:58:14 -0400, Keith Nuttle <Keith_Nuttle@sbcglobal.net> wrote: >On 8/17/2013 1:30 PM, Charles Ellson wrote: >> On Sat, 17 Aug 2013 16:43:54 GMT, myths@ic24.net (cecilia) wrote: >> >>> On Sat, 17 Aug 2013 09:13:59 +0100, Mick <mrcycleuk@yahoo.co.uk> >>> wrote: >>> >>>> Hi all, >>>> I have come across a article in our local Isle of Wight weekly paper >>>> the "County Press" >>>> [...] >>>> On them printing it I am very disappointed, it seems to be printed in >>>> "black and White" as opposed to "grayscale" >>>> I appreciate most printouts they do will be text and "black and White" >>>> [...] >>> >>> Even in black and white, choice of output type is not necessarily >>> intuitive. >>> >>> My HP Scanjet 3400C, using HP PrecisionScan LTX, offers >>> Text >>> Text and Image >>> Black and White Drawing >>> Black and White Photograph >>> Color Drawing >>> Normal Colour Photograph >>> Best Colour Photograph >>> >>> I don't think that I have ever found the results of Black and White >>> Drawing satisfactory, even for black and white drawings. >>> >> Can you adjust the black v. white threshold setting ? If it is fixed >> then that often makes 2-colour scanning useless especially if the >> paper is no longer white enough. >> >>> I use a photograph setting. For black and white drawings, I use >>> IrfanView to remove grey background that should be white, by editing >>> the palette. > >The reason a full spectrum color scan is better than black or white or a >two color scan is the fact that inks will bleed into the paper. This >tends to separate the colors making up the ink. (Yes even black ink >will separates into its various components which are different colors. >and yes I realize there is a limited number of colors detected in the >average scanner.) > >By scanning if a full spectrum you get all of the colored compounds >making up the ink. > Attacking from another direction, scanner software can allow scanning with red, green or blue either dropped out or enhanced thus allowing assorted stains, backgrounds or other defects to be lost. This will often assist with GRO documents where faint original details are overpowered by the background security printing. >The same can happen as the components of the ink react with the >components of the paper causing compound of different colors. > >Looking at an old copy, you may not even be aware of the many colors >making up the apparent black ink on the white paper. > >Once you get a full spectrum scan, you can manipulate the image in a >image processing program to get the most readable image.