There are advantages and disadvantages to each merged color format, so unless the output is specified you may choose either one. RGB Color If the Create composite option is not selected, ImageJ will create a single RGB color image. A composite stack allows you to access the channels separately, and to visualize the data in a variety of ways using the Channels Tool (Image > Color > Channels Tool). There are two ways to combine bands to create a color image:Ĭreate composite the merged channels will create a special type of stack called a composite stack. Note the dimensions and memory size of the original image. You will use this folder to save the scaled-down images. Create a new folder named Meteor Crater Small at the same level as the LT50360362011173PAC01 folder.You will also learn how to fix the dull, washed-out look of the color composite images. In this section, you will scale the seven Meteor Crater Landsat bands to a size that is easier for creating true and false color images. In general, the smaller the images the more you can stack. This is especially useful when working with large time series images that you want to stack and animate. You just scaled up a portion of a large image, but it's more common to need to scale down large images to a size that's more workable. Scaling images that are too big to work with Close all of the open image and stack windows.The size of the mini-stack is 24K and the size of the scaled stack is 2460K indeed, 100 times larger. (Conversely, scaling by 0.5 decreases the size of the image 0.5 2 times, or 25% (1/4) its original size. Doubling the scale increases the size of the image by 2 2 or 4 times. In other words, the size (memory) of the image increases by the square of the scaling factor. Since you scaled BOTH the height and width of the image by 10x, the area (or number of pixels, or the memory size) of the image is 10 x 10 = 100 times as large as the original. Look at the memory size of the mini-stack and the file size of the 10x stacks (Tip: The memory size of each open image window is displayed at the bottom of the Window menu.(If not, try the process again on one of the other 10x images you created.) Measure the diameter of the crater you just re-calibrated.This would be a good time to turn off the global setting. Activate any one of the 10x images and choose Analyze / Set Scale and change the scale to 3 meters per pixel.The new spatial calibration is 30/10 or 3 meters/pixel. (Tip: To select a perfect square centered on the crater, hold down Command-Shift (Mac) or Control-Shift (PC), click at the center of the crater, and drag outward.) Since the scale is set at 30m per pixel, 60 pixels equals 60 x 30 = 1800 meters. The selection size appears in the image status bar as you make the selection.
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