brianm@sco.COM (Brian Moffet) (03/30/89)
I am trying to take a color image with know RGB values
and translate it to a black and white image. I have looked at the
various other methods of denoting color (HSV, etc...)
but these do not seem to take into account the sensitivity of the
eye (which I suppose black and white file is similar to?)
It appears to me, that CIE (method? algorithm? theory?) does take
into account the sensitivity to the eye. However, I cannot see
how to translate a color to a particular shade of grey.
Could anyone give me some help on this? Do you take the normalized
vector for a particular color and this is your percentage
in the shade of grey? (r * 0.??? + g * 0.??? + b * 0.???) = grey.
I get the impression that the various percentages for r, g, and b
should be about .300, .450, and .250 respectively.
I know this has been discussed before, so thanks for bearing with me.
thanks much
brian moffet
--
'Evil Geniuses for a Better Tommorrow!'
My opinions do not in any way reflect those of my employer or my fish.
Brian Moffet brianm@sco.com {ucscc,uunet,decvax!microsof}!sco!brianmbenji@hpfcdq.HP.COM (Jeff Benjamin) (04/01/89)
> I am trying to take a color image with know RGB values > and translate it to a black and white image. > > Could anyone give me some help on this? Do you take the normalized > vector for a particular color and this is your percentage > in the shade of grey? (r * 0.??? + g * 0.??? + b * 0.???) = grey. > I get the impression that the various percentages for r, g, and b > should be about .300, .450, and .250 respectively. You're close...the equation you want turns out to be: I = 0.30 * r + 0.59 * g + 0.11 * b This takes eye sensitivity to different colors into account. I don't know much about the derivation of this; maybe someone else can elaborate. ----- Jeff Benjamin {ucbvax,hplabs}!hpfcla!benji Graphics Technology Division benji%hpfcla@hplabs.HP.COM Hewlett Packard Co. Fort Collins, Colorado
benji@hpfcdq.HP.COM (Jeff Benjamin) (04/16/89)
> Organization: Hewlett-Packard - Fort Collins, CO Lines: 20 > I am trying to take a color image with know RGB values > and translate it to a black and white image. > > Could anyone give me some help on this? Do you take the normalized > vector for a particular color and this is your percentage > in the shade of grey? (r * 0.??? + g * 0.??? + b * 0.???) = grey. > I get the impression that the various percentages for r, g, and b > should be about .300, .450, and .250 respectively. You're close...the equation you want turns out to be: I = 0.30 * r + 0.59 * g + 0.11 * b This takes eye sensitivity to different colors into account. I don't know much about the derivation of this; maybe someone else can elaborate)--- Jeff Benjamin {ucbvax,hplabs}!hpfcla!benji Graphics Technology Division benji%hpfcla@hplabs.HP.COM Hewlett Packard Co. Fort Collins, Colorado #! rnews 1133 Path: attcan!uune