Symbol 5720 from IEC 60417 - Title/Meaning: Image line density Function/description: To identify the control or the indicator to change the image line density, for example on diagnostic ultrasound equipment.
Additional information: 
Published in: Amendment 2, 2002,3C/473/FDIS,62A/228/CDV
Own work using: iso.org/obp/graphics/grs/00a8175c-284b-4e35-bcc8-daf5d3e7c91b 200.png
Vectorization:  Mrmw