Change signature from black to blue?

It depend on how you added the signatire if it is on its own layer you can clip a solid color to it. Here are three

Let's assume you are trying to select a black signature on a white background. There are numerous tools with which such a selection can be made. However, many of them will leave a halo of white partially selected around the signature. The following is a clean way to make such a selection.

• Hold down the Command/Control key and from within the Channels panel click once on the RGB channel at the top. This will make a selection based on the luminance values within your image.
• Inverse the selection via the Select menu.
• Within the Layers panel create a new layer and fill it with whatever colour you like. The selection that was in place will automatically be converted to a layer mask. Instead of a regular layer you could create a Solid Color layer which would allow you to easily change the signature color at any future point.

I suppose you want to do that in Photoshop, so I will move to the Photoshop forum.

So you have signed a piece of paper and you signed in black, scanned and want to change to a colour of your choice. Blue would be easy, as you just need in RGB to clear (set to white) the R and G channel. There will be blue left...

Here are more info on channels: Photoshop channel basics .

You could also add a spot colour channel. That would be great if your signature will be printed using a spot or special colour like gold. To do that, you would use a monochrome picture of your signature and copy that one to the corresponding spot channel.

The easy way to change the colour is, however, to select your signature

(Make quick selections in Photoshop ; Select color ranges in Photoshop ) and change the colour of the selection. Most of the time I do that with a colour layer (Adjustment and fill layers in Photoshop ).

And to be complete, you could even use the greyscale image of your signature as a selection mask for your adjustment layer (as the signature is black, you would need to invert the mask, as black is transparent and white opaque). Layer masks in Photoshop are greyscale images and when selected, you can draw on them or paste information to them or use a bunch of filters.

What program?