how can I measure selected area of pixels using photoshop elements 12?

I've found a way to do this in Elements 13 for Mac, as described below. Hopefully it will work in your version as well.

1. Go to Window>Histogram to open the histogram window.

2. Using any of the selection tools, select the portion(s) of an image that you wish to measure.

3. In the histogram window, click on the circular arrow above the upper right corner of the histogram itself. A small pop-up indicates that it's for "Uncached Refresh". You must do this to get a valid pixel count.

4. At the bottom of the histogram window, you should now see a cache level of 1 and an accurate pixel count for the selected area.

For my purposes, I want the area in square inches, so I divide the number of pixels by the square of the resolution in pixels/inch. I find this extremely useful for determining the area to be electroetched on a piece of copper or silver partially covered with a resist, in order to calculate amperage for the desired current density.

Show the 'information' panel F8).

In the middle horizontal section, select 'pixels' on the left drop-down menu.

Use the rectangular marquee tool to select your area: the dimensions in pixels of the rectangle is shown under 'dimensions' on the right.

I think there are other ways to measure a line segment, but you could use the above measure by adjusting the rectangular marquee tools to both extremities of the segment,

- use the move tool to rotate the rectangle so that the diagonal measuring the segment is horizontal,

- move the rectangle to the left, and check validate, which creates another rectangle including the first one

- read the pixel dimension (L:) in the info panel like above.

Display the Info window (F8), set X;Y unit of measure to pixels. As you then drag out your selection box the Dimensions section of the Info window will display the pixel Width & Height of the selection.

Cheers,
--
Neale
Insanity is hereditary, you get it from your children

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