Import Black & White pdf, change white background to transparent.

[Drizzt]

Hello,
I'm new to the forum but not to Photoshop. I have a bit of self-taight experiance. I use CS4. Is there a way in Photoshop or Illustrator to import a black and white pdf (i.e. a schematic diagram) and change the white background to transparent? The black lines would stay but the the background would be transparent. I really don't care what format the resulting image is in, tiff, gif, png, etc... I tried importing into PS and 'Save as' tiff and checking transparent. Did the same with GIF and PNG. Apparently, that only works if you create a image in PS or Illustrator and want to export it as a transparency. What I want to do is to change the background of an existing image to transparent.

Thanks in advance.

[Stric9]

yep.....use blend if in the blending options dialoge box. The slider marked This layer and move the white slider to the left. Use alt to split the handles for more control.

[NamanyayG]

Another Method -

Use any of the selection tool (magic wand, or quick selection)
Click on the white area.

All white will be automatically selected.

You can delete it, then save as PNG/GIF to preserve transparency, OR, you can refine the edge even further.

To refine edge, just click the refine edge box (while selection is on), and then, maybe add a bit of a feather, or increase smoothing, or both.

Cheers.