Identifying Land Use: Using Image J

After opening the NE portion of the Los Angeles Quadrangle use the rectangular area tool to select a portion of the image that measures 400 by 600. Open a new file and specify the width as 400 and the height as 600. Paste the copy into that new space and save as sample#.tif.

Close all files and open sample#.tif. From the Image drop-down menu select lookup tables and change the table to fire. Save this new image as sample#_fire.tif.

Close all images and open the fire#.tif file. From the Image drop-down menu select Adjust and then Threshold. The Threshold pop-up menu will appear and adjust the sliding bars so that the vegetative areas are selected (41 – 122). Change the image to BW (black and white) and then click, apply. Save this image as sample_bw.tif.

From the Analyze drop-down menu select Histogram. Since the file is saved in black and white, the count is only of white and black pixels. Using the pointer, move to the value of 248, this represents all the pixels that show vegetation. The count recorder will identify the total number of black pixels. From the dimensions of the file (400 x 600) calculate the total number of pixels. Dividing the number of black pixels by the total will give the percentage of the area that is vegetative.

DATA:

	Pixel Value	Count
Min	0	-
Max	248	262003
Total		310536

Percentage Green Space:

_______________ / _______________ = _______________

max total