PixelZoomer: A Firefox Extension For Measuring Pixels, Zooming And Grabbing Colors
PixelZoomer is a very handy Firefox extension for web developers which can replace the step of taking screenshots of a web page and pasting it into an image editing software for making pixel-perfect measurements.
Once it is activated (clicking an icon at the bottom of Firefox), a custom window with the web page screenshot is loaded.
Inside this window, you can zoom in/out, select specific areas to see their width/height and pick the color of a pixel.
The extension has an option to grab the screenshots using Java runtime (more accurate) or Canvas (faster).