Tutorial: Displaying an Image Set

This tutorial extends the concepts learned in Tutorial: Displaying an Image. Here you will learn how to open multiple images to work them as an Image Set, animate them like a movie, make some measurements, and save the files.

Opening Files

Click File > Open... to show the familiar Open dialog shown below. Select the 4 images as shown below and click [Open].

Note: Marking these 4 files involves the standard Windows multi-selection protocol using the [Shift] key. To mark files that are not in a contiguous block, use the [Ctrl] and [Shift] keys in the normal way.

At the bottom of the dialog, notice that Open as Image Set option is enabled (drop the list box to see it as a check box option). This instructs Mira to load the selected images into the same Image Window. Multiple images constitute an Image Set, which is a Mira concept for working with multiple images as one object. If the Load As Image Set item is not checked, then the selected files are opened "traditionally" into different windows. Since an Image Set is chosen, the Image Window opens with an Animation Toolbar along its bottom border. This toolbar lets you select the active image (that is, the one on top) or to move between them. You can switch between images one at a time or by playing them as a movie using a chosen frame rate and step.

NOTE	If a FITS format image opens upside down, open the Open dialog and check the Flip FITS Images option, then re-open the image.

Changing the Image Set

Mira provides tools for adding, deleting, and reordering the image set. These are most conveniently accessed using the Image Set Toolbar, which can be quickly opened or closed using a keyboard accelerator or a menu command. Now, press the key combination Ctrl+Q to open the Image Set Toolbar. The toolbar opens attached to the left border of the current Image Window as shown below.

Using the toolbar is simple and some of its commands work in conjunction with the Image Animation Toolbar at the bottom of the Image Window. For example, to insert one or more images into the image set before the second image, move the selection trackbar on the Animation Toolbar to position 2, then click (insert before) on the Image Set Toolbar. To delete an image from the set, position the trackbar pointer and click (delete). When you are not using the Image Set Toolbar, you may wish to press Ctrl+Q again to close it.

One additional way to insert images into an image window is by using the Copy+Paste commands in the Edit menu. The Copy command places a copy of the current visible image from any image window onto the Windows clipboard. This clipboard image can be pasted into any other image window to append the image set already there.

Blinking and Animating Images

On the Animation Toolbar, click ("Fast Forward") to animate the images in the forward direction through the Image Set. If the toolbar appears as above, then the frames will be stepping forward at 8.5 frames per second at a step of 1 (in other words, every frame is shown). Now move the mouse pointer onto the Colormap at the right side of the window, do mouse down, and adjust the palette contrast and brightness while the images are animating ( you can also open the Palette Properties dialog and change the palette or palette settings while animation is running). You can also do things like re-center and magnify the images during animation. And, of course, the coordinates continue to update as you roam the pointer over the image. Next. let us slow the animation rate to 4 frames per second. To do this, press and hold the down arrow on the frame rate spin control. You will see the frame rate reduce and the image animation will also slow. Now stop the animation by clicking on the animation toolbar. Let's step forward through the images by clicking the button. As you do this, new images move to the top of the stack where they become the "active image" for the image set loaded into the window. The same result can be achieved by moving the red trackbar on the right side of the toolbar.

Using a File List

Now that we have opened an image set, let's see how we can easily work with this same image set in the future. Click File > Open to go back to the Open dialog. If we had any plans to use this same set of image in the future, here is what we should have done in the first place: Create a File List containing the target images. The File List contains the full path name of selected files. Mira works with a File List just a like a file, except that it knows that the File List contains the names of other files. In fact, a file list can contain other file lists, even mixed with individual image names.

Let us create a File List containing 4 image files. First, open the standard Open dialog and click on the 4 images to open, like this (Use the standard Windows [Shift] and [Ctrl] key combinations to mark multiple files):

After marking the target images, click [File List >>] on the bottom of the dialog. This opens the File List Editor as shown below.

I the above figure the path names are scrolled to the right to show the file name on the right end. As you can see, the Comments and File List Name fields are initially blank. To create a File List, you must enter a name into the File List Name field and optionally, you can add some comments to the Comments field. When you are finished, click [OK] to save the new File List and return to the Open dialog. In the Open dialog, there is a new file with the name you gave to the File List. Here we have named it 4 Hyakutake files; when you click [OK], Mira creates a file named '4 Hyakutake files.axf'. After a short time, the new file name automatically appears in the Open dialog, as shown below. In the future, you will be able to open these same 4 images simply by selecting the File List by name. Let's try that now: Click on the new file list to select it as shown below.

Now, click the [Open] button. The next figure shows the result of opening the file list:

There are more things you can do with a File List, such as opening two of them into the same window. See Working with File Lists.

Measuring Image Statistics

Now let us measure the statistics in the same rectangular region of interest on the 4 images that we just loaded. To do this, make sure the Image Window containing the 4 images has the focus (in other words, it is on top of the stack). On the Image Toolbar, there are two buttons to use. First, check that is pressed (blue color). If pressed, Mira measures the entire image set; conversely, if the button is popped out (gray), then only the current, top image is measured. Next click to perform the measurement. The Statistics Measurements are tabulated in the Statistics Report window shown as below.

Conversely, if the measure button is popped out, like , then Mira measures only the current image. If you were to move the image cursor to 4 places on the image, and click each time, you would instead create a report of measurements for only the top image, hyak0324.125.fts:

Of course, the region being measured may be changed by adjusting the Image Cursor and then re-measuring. Additional statistics measurements are written to this same window. You can also measure only 1 image by popping out the so that it appears black. You can determine the current state of this Image Set Flag by letting the mouse pointer hover over the button. The button is similar except that it controls processing rather than measuring and plotting.

Plotting a Row Profile

One of the many types of plots Mira can display is a Row Profile Plot, which shows the variation in image luminance along a row. The Column Profile Plot shows the variation along a column. For Column Profile Plots and Row Profile Plots, and for some other plots and measurements, the region of interest is marked using the Image Cursor. Before making the plot, we must answer the following question: Do we want to plot the average row profile for a single image or do we want to plot the same row profile for the entire image set? The choice is made using the Image Set Plot button on the Image Toolbar. Click the button to pop it out and turn off image set plotting. That way, only the current image will be plotted. Click on theImage Toolbar (or on the main toolbar) to plot a single row at the center of the Image Cursor. This button executes the Row Profile Plot command. If instead, you clicked to make it appear pressed, then you would get 4 plot series, one at the same position in each member of the image set, as shown below. Notice in the plot caption (not the window caption) that [497:548, 516] reminds us that we plotted between columns 497 and 548, along row 516. This plot shows only row 516 for all members of the image set.

In the window above, each plot series uses a different color. You can choose these colors or set them all to the same color using the Plot Attributes dialog. You can also animate the plot series much as you would the Image Set using the Plot Animation Toolbar. Notice that the window title has the suffix [RP], which means "Row Profile".

Another interesting plot might be the Average Row Profile, which plots the mathematical average of all rows inside the Image Cursor. To choose the active image or all images, we again set the button accordingly. The figure below shows the Average Row Profile ([ARP]) inside the same Image Cursor region.

Saving Images

Finally, lets suppose we performed some processing on the image set images and we will save the images back to files. We can save to the original files or to other files. The alternatives are described in Saving Image Sets. Here will will save the image set over the original files: Click File > Save Image Set > Save All. Using other commands in the Save Image Set submenu, we can save all images to a different folder, append a suffix to the file names, or create a new File List.