RGB to Grayscale

RGB to Grayscale

Post by Bob Rasmusse » Thu, 26 Nov 1998 04:00:00



Afternoon, all...

Can anyone tell me what formula PhotoShop uses to convert
RGB files to Grayscale?  I have dumped a RGB file and a Mode
converted grayscale file and compared the values.  The
grayscale results do not seem to fit the PhotoShop Luminosity
formula   red * .30 + green * .59 + blue * .11    or the
standard NTSC formula   red * .299 + green * .587 + blue * .114 .

Any help appreciated.

Bob

 
 
 

RGB to Grayscale

Post by John D. Belmon » Sun, 29 Nov 1998 04:00:00


Hi Bob,
the 30-59-11 formula you have there I believe is the standard. Try testing it
with channel mixer by creating a monochrome and setting the rgb values in this
formula. See what you get.
Sincerely,
John D. Belmont

--
all things digital
http://www.drizzle.com/~johnlox


> Afternoon, all...

> Can anyone tell me what formula PhotoShop uses to convert
> RGB files to Grayscale?  I have dumped a RGB file and a Mode
> converted grayscale file and compared the values.  The
> grayscale results do not seem to fit the PhotoShop Luminosity
> formula   red * .30 + green * .59 + blue * .11    or the
> standard NTSC formula   red * .299 + green * .587 + blue * .114 .

> Any help appreciated.

> Bob


 
 
 

RGB to Grayscale

Post by Chris C » Sun, 29 Nov 1998 04:00:00


The values Photoshop uses for RGB to Grayscale depend on your RGB working
space (or your monitor setup in older versions).

Chris


> Hi Bob,
> the 30-59-11 formula you have there I believe is the standard. Try testing it
> with channel mixer by creating a monochrome and setting the rgb values in this
> formula. See what you get.
> Sincerely,
> John D. Belmont

> --
> all things digital
> http://www.drizzle.com/~johnlox


> > Afternoon, all...

> > Can anyone tell me what formula PhotoShop uses to convert
> > RGB files to Grayscale?  I have dumped a RGB file and a Mode
> > converted grayscale file and compared the values.  The
> > grayscale results do not seem to fit the PhotoShop Luminosity
> > formula   red * .30 + green * .59 + blue * .11    or the
> > standard NTSC formula   red * .299 + green * .587 + blue * .114 .

> > Any help appreciated.

> > Bob