3 user pixel masking, User pixel masking – ARRI ALEXA Mini LF Ready to Shoot V-Mount Set (LPL) User Manual
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Sensor Settings
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20.3 User Pixel Masking
All sensors exhibit a certain number of defect pixels, and ARRI cameras have two mechanisms to catch
and correct them: one is a static pixel correction based on a pixel mask created during manufacturing,
and the other is a dynamic pixel correction that continuously evaluates each frame and masks defect
pixels that are not caught by the static pixel mask. In very few cases, we have observed some pixels
that are not corrected by either method; for those cases User Pixel Masking is available.
User pixel masks can be created with the
Ubuntu.
When shooting ARRIRAW, it is not necessary to load the User Pixel Mask into the camera. Instead, it
can be applied to the ARRIRAW files in post using the ARRIRAW converter or any third party software
that has implemented the User Pixel Mask feature through our ARRIRAW SDK.
The User Pixel Mask will remain intact after a factory reset and after a camera software update. It can
be manually removed or overwritten with a new one at any time.
1. Select
MENU > System > Sensor > User Pixel Masking.
Following options are available:
User Pixel Mask Active
Shows whether a User Pixel Mask is currently active in the camera.
Install User Pixel Mask
Select to install a User Pixel Mask from USB memory stick.
Export User Pixel Mask
Select to backup the currently installed User Pixel Mask onto USB
memory stick.
Delete User Pixel Mask
Select to uninstall a User Pixel Mask.
Grab Raw Image
Stores an ARRIRAW frame grab on the USB memory stick.
User Pixel Mask Generation
1. Insert a USB memory stick into camera.
2. Select
MENU > System > Sensor > User Pixel Masking > Grab Raw Frame
to grab an ARRIRAW
frame.
The ARRIRAW frame grab is stored on the USB memory stick in folder ARRI/A-MINI-LF/SENSOR.
Alternatively, you can record a short ARRIRAW sequence and use that material for marking defect
pixels.
3. Import the ARRIRAW frame grab into the ARRIRAW Converter.
4. Use the ARRIRAW Converter to mark defect pixels. The marked pixel coordinates are stored in an
XML file called the User Pixel Mask. Please note that it is advisable to mark the least number of
pixels necessary, as too many marked pixels can be counter productive.
5. Save the User Pixel Mask to the USB memory stick in folder ARRI/A-MINI-LF/SENSOR.
6. Insert the USB memory stick into the camera.
7. Select
MENU > System > Sensor > User Pixel Masking > Install User Pixel Mask
to load the mask
into the camera.
8. After a restart of the camera, the marked pixels will be masked using information from surrounding
pixels. This masking is applied to the images delivered from the sensor, before any other
processing takes place, and thus becomes active on all outputs.
9. Carefully check the end result by visually inspecting the areas where you have marked pixels; if too
many pixels are marked too close to each other, or if pixels are marked close to other pixels that are
already marked in the static pixel mask, the result could be uncorrectable clusters, which are more
visible than the original defect pixels.