Need a help, changing background

[Aqwa]

I have a drawing, its a blue color ball pen on yellow paper. I scanned it. Now I wanna make a background white, so that I can print it like that.
How to change background of this scanned picture to be white, and keep the blue color of the lines made by pen (blue).
Is there a way to "tell" photoshop to recognize all the "yellows" on this photo and make it white?? Crazyyy....

 

[Eggy]

Add a hue/saturation adjustment layer and select the yellows, use the slider to desaturate totally and the lightness to maximum

 

[Nxxl]

Select your Quick Selection Tool and right click on your image. You will get a list of options. At the bottom of the Options Box, you will see an option that says "Color Range".



Now once you open up Color Range, you will get a list of colors or an option to Sample colors. In your case, the colors you want to select are Blue. So select Blue and Hit OK.



This will create a selection around anything that is blue in your picture. Once the selection is made, you can either make it a new layer by pressing Ctrl+J or you can invert the selection via Ctrl+Shift+I and paint everything white.

If you are unable to make a proper selection of the blue color due to it having different shades of blue, you can manually select each color using the "Sampled Color" option. To Sample multiple colors, press and hold Shift+Alt till you see a small + sign next to the eyedropper cursor. Keeping these buttons pressed, select the different shades of blue.

 

[Aqwa]

Oh, man, you're incredible! What a quick and precise solutions. I will try both ways, and let you know my impressions.
Thank you veeeery much, Eggy and Nxxl !