Overexposed images for small ROI

[Karl-Philippe]

Hello,

I use a PLUS server (Microsoft Media Foundation compatible imaging device) to acquire ultrasound images with a frame grabber. However, I am experiencing a problem as the smaller the region of interest (ClipRectangleOrigin and ClipRectangleSize), the more the images are overexposed (high brightness). When no cropping is applied using the ClipRectangleOrigin/Size parameters, the images captured in Slicer look exactly the same as they do on the ultrasound system monitor. Is this a known problem and what would be the solution to not having overexposed images?

Thank you,

My hardware is:

• Ultrasound system Acuson S3000
• Frame grabber AV.io HD epiphan video
• Window computer

Here is my device configuration:

<Device
  Id="VideoDevice" 
  Type="MmfVideo" 
  VideoFormat="YUY2"
  FrameSize="1280 720"
  CaptureDeviceId="0" >
  <DataSources>
    <DataSource Type="Video" Id="Video" PortUsImageOrientation="UN" ImageType="BRIGHTNESS" 
      ClipRectangleOrigin = "405 38" 
      ClipRectangleSize = "460 450" />
  </DataSources>      
  <OutputChannels>
    <OutputChannel Id="VideoStream" VideoDataSourceId="Video" />
  </OutputChannels>
</Device>

[Sunderlandkyl]

Probably the window-level set in Slicer is not the same with the cropped ultrasound.

You can check and adjust the exact window level values in the Volumes module (in the display section):

You can also use the window-level mouse mode to adjust the contrast by clicking and dragging on the image: