Deep Image Comparison

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Enhanced images also known as 'deep images' are a step beyond plain PNG images and are rich with information.

They contain 3 layers of information:

EnSight has the option to generate 'enhanced images' which contain the above information. Once you've used EnSight to generate a collection of such images, you can then create a slider layout with them using the Template Editor. Nexus then automatically recognizes the image's format and makes the appropriate features available in the Slider Layout based on the format.

When a Slider Layout consists of deep images, you will have to explicitly turn on the property deep_image_comparison to enable this feature. If not, they will be treated like normal images. Also, if any image in the set is not a deep image, deep_image_comparison will be automatically disabled.

Look at the images below. Initially, what you see is a simple image with a combination of RGB colors. The Probe and Pin will show the RGB values, just like the previous example.

Because the image is enhanced, as each image is loaded, the variables available in each image are added to the dropdown menu.



When a variable is selected, all parts that contain the selected variable are shaded. In the example below, the clip plane which contains PRESSURE_Relative is fully shaded in gray scale. The color or intensity of shading is based on the value of PRESSURE_Relative which may vary from region to region. The current mapping of the shading color to the value is displayed in the palette bar below the image. If a variable or any part that contains the variable is not displayed in the image, you will see a warning.

Use Probe to view the value at each point. Previously when the RGB option was selected in the dropdown, the RGB values were displayed. Now that a variable is selected, the variables are read from the enhanced image and then displayed, along with the values and the part associated with it as well. Each pixel's 'deep' information can be read this way.



Let's consider the image on the left. Click on the settings icon on the left. A dialog will open up with the current settings. There are several things you can customize:

Once you click Apply, the settings should be saved and the image will be regenerated with the updated settings. You may use the Reset button at any time to reset the settings back to defaults.



Let's see what happens when the highest and lowest values are used as Max and Min respectively, and a different palette is chosen. Check the preview scale to see if everything is ok.



Click Apply. Now you'll see that the palette is updated and the image is regenerated. Let's zoom in for a better view.



Let's invert the color scale now.



Check the preview scale. Click Apply. Now, you'll see the changes with the new scale applied.



Now let's try hiding the remaining pixels. Check the option in the settings dialog. You will see a Background option. This decides what the 'hidden' area will look like. This can be any value between 0 (full white) and 1 (full black).

Let's switch to the same image on the right and let's try a different background for the right image with similar color and min-max settings.



Click Apply. Notice that the other parts that do not contain the selected variable are now replaced with the selected background. The left image has a background of 0 and the right has a background of 0.5. Everything else except the clip plane is now hidden.



Note that all the features mentioned above apply to both right and left images. Let's un-check the hiding option on both sides.

Deep Image Differences


Now look at the second dropdown considering the left image again. This is what we call a View. The default view is the current image which is 'Left image' and 'Right image' for images on the left and right respectively.



Let's look at the available views:


You may choose any view you like for any image, and the image next to whichever dropdown you're playing with will regenerate itself. Let's select Left - Right image. In order to see the palette apply properly, let's set the Min to -50 and Max to 50. Let's also try a different color palette.

Note that the highest and lowest values available are zero because both the images are the same and the difference in PRESSURE_Relative is zero.



Hit Apply again. Since the images on both the left and right are the same, the difference must be zero. Notice that the clip plane is shaded by a color, which, if you look at closely, matches the color at the center of the color scale, which is zero. This is how it works. Let's also verify with the Probe and Pin. These will read as 0.



Here's another example of the Left - Right image view, but with a different image. Hence, the difference values will be non-zero. Let's try changing the image on the right. When there is a change in image, the computation is run again with the new image. Notice that the Pin updated its value and the clip plane's shade was updated as well to reflect the change.




Now, switch over to the Right - Left image view. This is the opposite of the previous Left - Right image view. For example, if the computed difference value for PRESSURE_Relative in the Left - Right image view was 50 Pa, the corresponding value in the Right - Left image view would be -50 Pa.

Note that the color settings will persist in this view as well, because we have the Sync color settings across views option checked. Uncheck it if you want the view to have its own color setting.



The Abs(Right - Left image) view is also very similar. The only difference is that the computed values for the chosen variable are calculated as the absolute value of the difference between the value in the right image and the left image. For example, if the computed difference value for PRESSURE_Relative in the Right - Left image view was -50 Pa, the corresponding value in the Abs(Right - Left image) view would be 50 Pa.