(Original Picture)

Step 1: Open the photo that has water drops on the leaf. Press L (for short cut) for Poloygonal Lasso Tool and select the water that you want to change the color.

Step 2: Press the Right Mouse Click and select the Feather.

Step 3: Choose the pixels to 2 in Feather Radius. (Hence, the reason I chose the Feather Radius to 2 was to get soft edge for the water drop)

Step 4: Press CTRL + U to get Hue/Saturation Dialog Box and manipulate the Hue/Saturation values to color the water drop. (Hence, think about the realistic result by looking the value changes)

Here is the final result. :)

(Original Picture)

Step 1: Open the photo that you would like to convert into Pencil Drawing in Adobe Photoshop.

Step 2: Press the short cut key Control + J key (CTRL + J) to duplicate the layer. After that, press CTRL + U and decrease the saturation value to -100.

Step 3: Press  CTRL + J again to duplicate the layer and press CTRL + I to make negative effect.

Step 4: Then choose the layer style to Color Dodge. You won’t see anything now (all become white).

Step 5: So, to view pencil strokes (or) depth of pencil tones please apply a Gaussian Blur (From Menu: Filters › Blur › Gaussian Blur) to the top of the layer to become a pencil drawing. Hence, the more you increase the pixel value they more you will see the dark tones of pencil strokes. If you want to have thin sketch lines (soft tones) .. please use lower pixel value.

NOTE: To see the effective result please check the Preview in Gaussian Blur Dialog box.