choose a channel from the channels menu and work with that.
image> adjustments> threshold.
image> adjustments> channel mixer – select greyscale. in cs3 there’s a convert to greyscale tool.
or as id says: image> mode> grayscale.
much obliged gentlemen!
but once i get it grey, how do i make it pure black?
Use levels or curves dialog box and select the lighter pixels using the black eyedropper.
you could just use the Magic Wand, de-selecting the "Contiguous" option, to click in the white you want to keep. you may have to reduce the tolerance and try the selection over if it does not get enough of. If it gets areas that you want turned black, clean up the selection with the lasso tool or whatever selection tool works the best for you.
once the selection is made, use the Select->Inverse menu option (CTRL+SHIFT+I). now, use the Layer->New Fill Layer..>Solid Color menu option click OK on the default options, and then choose the color (black, for instance) that you want to fill this selection.
HTH
convert file into cmyk then go to image/adjustments/hue and saturation. check colorize and then set the hue and saturation to 0.
after doing this, check channels and you’ll see that only black will remains.
Show us the image in question? If it’s an image with 100% white background and an object in the middle, then you have what you need now.
This is what i would do:
Non-destructively:
Adjustment layer -> hue/saturation: saturation = 0
Adjustment layer -> curves (or levels)
Move black point inwards until what you want black is black. Move white point inwards as well if the background wasn’t 100% white.
If any white points inside the object remains: add new layer, paint with a black brush.
Destructively:
Image->Adjustments->desaturate
Image->Adjustments->curves (or levels)
Move black point inwards until what you want black is black. Move white point inwards as well if the background wasn’t 100% white.
If any white points inside the object remains: paint with a black brush.
Comment to other solutions:
* ** Ignore the suggestion by gladys saan (no need to convert to cmyk). It will basically leave you with a similar result as simply converting to greyscale…
* ** Fred M. Stevens suggestion will create very ugly edges as it is the "magic" wand… * ** Dave milbut: Don’t use threshold unless you want a 1-bit result (without any anti-aliasing)… You might get away with it if you have a VERY high resolution image…
