#7: Image Graph Transformations¶

Image Graph Transformations¶

The Image Graph provides transformations to further customize the image projection in the plot widget. These options can be accessed by the following actions:

Go to design mode
Right-click the image widget
Hover “Image Graph: Properties”
Select “Transformations”

The transformation dialog will then appear:

Transformations Dialog¶

The following values can be set:

Scale - dictates the ratio of the pixel dimensions to its plotted value.
Offset - sets the starting value of the image for each axis
Aspect Ratio - describes the width and height proportion of the image.
- “None” will auto-fit the image in the given space
  
  Aspect Ratio: None¶
- “Pixel-dependent” will respect the image dimensions.
  
  This is the most common aspect ratio as it does not modify the appearance of the received image data.
  
  For instance, a 100 x 150 image will still have 1:1.5 ratio regardless of input scale.
  
  Aspect Ratio: Pixel-dependent¶
- “Scale-dependent” will apply the ratio on the image.
  
  This is a more advanced aspect ratio as it modifies the appearance of the image heavily with the input scale.
  
  For instance, a 100 x 150 image will be stretched to satisfy the input scale of 1:3.
  
  Aspect Ratio: Scale-dependent¶

The default value is 1:1 scale with no offsets and uses the pixel-dependent aspect ratio. The scale legend can also be toggled from the dialog.

Use Case: Changing y-axis to mm-scale¶

A user wants to change the y-axis of an image to mm-scale, with a 1 pixel : 3 mm ratio. He also wants to adjust the image proportions to the new scale. Then the following can be done:

1. Rename the axis to units of interest (in this case, mm)

Go to design mode
Right-click the image widget
Hover “Image Graph: Properties”
Select “Axes Labels”

2. Set the transformation factor.

Open the “Transformations” dialog.
Set the y-axis scale to 3
Set the aspect ratio to Scale-dependent. This is to adjust the image proportions.

The following image widget is now: