Do you want to know how it's done? Learn how to use Photoshop the easy way!
When I first got into Photoshop I, like many others, learned by trial and error. And still to this day I am always learning new ways to do things quicker and more efficient. This project I am going to do now, I did long ago using a whole different technique of time consuming manual erasing. I swear it took me over an hour to do. The way I am going to show you will take maybe 10 minutes at most once you get the hang of it. Here is the picture I will begin with.
What we are trying to do is create a black and white image, and have all of the beautiful tulips be colorized, but nothing else. The first thing you will want to do is duplicate your background layer. Select Layer/Duplicate Layer and click OK. Make sure that your new duplicated top layer is highlighted.
Choose Image/Adjustments/Black & White, and click OK. You should now have a black and white image on top of your color image.
Next you will want to turn off the top black and white layer by clicking on the little eyeball on that layer, and make sure the bottom color layer is now highlighted.
Now choose Select/Color Range. The Color Range window should pop up, and your mouse should now be an eye dropper. While holding down the shift key, I am going to drag across one of the yellow flowers. Try to drag across as much as possible to get all the colors. I have my "Fuzziness" slider set to around 12. You may need to play with this a bit depending on the resolution of your photo. If you find that it seems to be too sensitive and selecting too much, turn this number down a bit and vice versa.
For my picture I had to also pick another yellow flower that had brighter colors in it to capture all of the yellows.
The selection works pretty good, but unfortunately, there are some yellows in the grass area of my photo that I don't want selected. I am just looking for the yellow flowers.
What you need to do to remedy this is to go into the Quick Mask mode by hitting "Q". Select your paint brush, and make sure the foreground color tile is set to black.
While in the Quick mask mode, you can just erase away any unwanted selections. Now that is cool!. Sometimes it may be hard to see all of the small things selected in the Quick Mask mode. Photoshop uses a red filter of sorts to let you know that you are in the Quick Mask mode. Just hit the "Q" key to toggle back and forth to help you see the "dancing ants" that indicate a selection.
Here is my selection now. Much better.
Turn your top black and white layer back on, and highlight it with everything still selected. Now hit delete. What this does is take everything you have highlighted on the black and white layer, and punches it through to show the colors underneath on the color layer. Once again, very cool! Hit Ctrl+D to deselect.
You may have to go in and use the eraser tool a bit on the black and white layer to get any places that may have been missed by the Color Range selector.
Now repeat this same easy process to get whatever other colors you may want.
One thing to keep in mind is that you can do ALL of the colors you want in one step if you want to. I just did the yellows in one step for the purpose of this tutorial. Here is what I ended up with. Now that is not too shabby for just a few minutes worth of work.