Image J Tutorial

CHEE 291 -INSTRUMENTATION AND MEASUREMENT 1 – Fall 2015

Image J

• An open source software which provides tools for analysing and treating digital images

• Download from this website: http://imagej.nih.gov/ij/

• Documentation on Image J’s different functions can be found directly on that website: http://imagej.nih.gov/ij/docs/guide/user-guide.pdf

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Image J ToolbarMenu Bar

Tool Bar

Status Bar

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Setting the Scale 4

ROIs (Regions of Interest)• ROIs can be created by using the first few (left-most) icons on the

standard ImageJ toolbar, namely the area selection tools:

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Manual Measurements 6

The left-most tools can be used to make measurements. Use the line tool to draw one of the coin’s diameter, then go to Analyze->measure. A pop-up window will contain various metric about the line you just drew. As you draw more lines and repeat the list of results gets longer.

Automated Measurement 7

Automated measurement starts by converting the color image to a grey-scale image.

ThresholdingSimple thresholding marks all pixels with values less than the threshold as off or 0, and all pixels with values equal to or above the threshold as on or 1. Move the sliders up and down to adjust the selection, then click apply

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Fill Holes 9

The thresholding misses some pixels due to reflection and uneven illumination. You can fill holes inside the coins.

Watershed

Without using watershed these two coins would be treated as single particle in the next step

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Analyze Particles 11

ImageJ kindly includes an ‘analyze particles’ function since it’s so common

Analyze Particles 12