Eyedropper Tool, Color Sampler Tool, Ruler Tool, Note Tool, 123 Count Tool

Shortcut – I.

If you’re doing color correction in an image then the Eyedropper Tool is your best friend. To use it properly first set the Sample Size in the option bar (the option bar I keep talking about is situated just below the Menus) to 3×3 or even better 5×5.

Hover the Eyedropper tool over the image and notice how the R G B values change. If you click with this tool anywhere on the image you will set the Foreground color to the color below the Eyedropper Cursor. A quick way to access the Eyedropper tool while having the Brush Tool selected it is to press the Alt key.

Hold Shift and left click while using the Eyedropper tool to access the Color Sampler Tool and create a new color sampler (you can have a maximum of 4 color samplers). You can see in the image below where my color sampler is and what are the R G B values in the area I have sampled from. This information is very useful when you do color correction or you want to know what are the values of a specific area. Even better, you can change the Mode to Lab, CMYK, HSB or other wacky modes. I remember that I used this tool a lot when I was first learning about Photoshop to see how various adjustments and blend modes affect the pixels values.

The Ruler Tool is for measuring the actual dimensions on the screen. Not a lot of uses for this tool (maybe if you’re a web designer) but it has one nice feature. In the options bar there’s a button called Straighten. Here’s how to use it. Notice that in the picture below, the level of the ground is not horizontal. It looks like the house is falling to the left side.

To correct this, select the Ruler Tool then click and drag where the horizon line is in the picture

Press Straighten and voila, we’ve straighten the horizon line. A bit of cropping occurs at the edges but that’s a good trade off for a straight image.

I never use the Note Tool but you may find it helpful if you’re passing documents to other people and you want to indicate something. In the image below I added several notes and each could indicate a specific problem you want someone to address or maybe if you’re extremely forgetful write notes to yourself, like “Don’t forget to reduce the saturation here” or “Remove this ugly spot here”.

Finally, the 123 Count tool is for counting objects. It probably has its uses for certain people but I haven’t ever felt the need to count objects in an image with a tool.
NOTE: The original house picture was straight to start with, but for the purposes of the tutorial I rotated the picture slightly to the left and then used the Ruler Tool on it.