Tab: Pixel History

The Pixel History tab displays a zoomed-in view of the Render Target View and a list of ergs affecting the selected pixel. Initially this tab is blank. To populate the tab, select a pixel in the Render Target Viewer pane. After that you can select pixels right under this tab. When you click on a pixel in the Pixel History tab, the image is re-centered on the selected pixel. For example, in the screenshot below, the gray crosshair is centered on the selected pixel at (401, 126).

Clicking on a pixel in the Pixel History tab updates the crosshair in the Render Target View. For example, if you select pixel (396, 122) in the Pixel History tab, then the crosshair in the Render Target View moves to (396, 122).

The Pixel History tab’s image is locked in place and you cannot pan or zoom it in/out.

The Pixel History tab contains the following elements:

Pixel History Thumbnail List
Pixel History Render Target View
Select Ergs Button
Refresh Button
Pixel Information Field
Image Information Bar
Histogram Pane

Pixel History Thumbnail List

This item contains small images that are ergs affecting the pixel.

On the right of each image, there are rows of text providing the following information:

  • erg number

  • erg type (clear, DrawIndexedPrimitive, etc.)

  • the number of times the call touched the pixel
    A pixel is “touched” by a call if the following tests passed: Z-test, Alfa test, Stencil test, and Scissor test.

  • if the pixel was rejected prior to touching the pixel, the reason for the rejection (for example, "Pixel was Z-rejected")
    A pixel is “rejected” if at least one of the following tests failed: Z-test, Alfa test, Stencil test, and Scissor test.

  • the final color of the selected pixel

 To select a certain erg, or to add an erg to the selection set, right-click on any thumbnail, and select the appropriate context menu option.


Pixel History Render Target View

This view shows the render target with two crosshairs overlaid to indicate the pixel location. The center of each crosshair uses a square to highlight the pixel. A red crosshair shows the current mouse position and tooltip shows the current coordinates within the image. A gray crosshair shows the previously selected pixel’s position. See the image above.

Select Ergs Button

Click this button to select the ergs that have affected the selected pixel.

Refresh Button

Click this button to re-calculate the pixel history for pixels selected in the Render Target View to reflect the current tool state. This button is active only after you modify something in the scene (for example, use an item in the Experiments Tab or set an override mode).

Pixel Information Field

This item shows the pixel coordinates, the erg range, and the number of times the call touched the pixel.

Image Information Bar

The Image Information Bar shows:

  • the image format

  • the image resolution

  • the color of the pixel under the cursor

  • the pixel history coordinates entered by a user (X, Y coordinates)

Enter (X, Y) coordinates in the editable fields and click Go/press Enter to get the pixel history for that location.

Histogram Pane

This pane contains the histogram of the frame buffer image. To open the histogram, pull the slider from the right of the image to the left, or double-click it.

The histogram enables you:

  • to visualize the color data within the frame buffer

  • to set the highlight and shadow clamping points for viewing the buffer; use the Shadow and Highlights sliders at the bottom of the histogram

  • to increase the dynamic range of the buffer you are viewing, so you can better see the data inside 

Histogram Color Channel Selection Drop-down List

This drop-down list enables you to configure the channels viewed for the selected frame buffer. These are the available options:

  • RGB mode - ignores the alpha channel if one is present

  • RGBA mode - weights the color values by the alpha channel; if all the alpha values of the image are 0, then no color information will be visible and so the image will appear white

  • Red/Green/Blue Color Channels - shows the image information in red/green/blue color

  • Grayscale –a grayscale conversion of the RGB data that was present in the buffer

  • Alpha Channel - a grayscale conversion of only the alpha data of the buffer


Selecting ergs and changing highlighting colors lead to the image and histogram changes.

Auto Clamp Button

Click this button to automatically adjust the Shadow and Highlighted sliders of the current histogram so that they clamp the view of the buffer to the lowest and highest data points in its histogram.

See Also

Render Target Viewer Panel
Experiments Tab

For more complete information about compiler optimizations, see our Optimization Notice.