IMX95 uGuzzi ISP : The AE algorithm can't achieve the maximum exposure

LiMengYi — Wed, 12 Aug 2026 08:20:46 GMT

I have configured AE LIMITS with the maximum exposure set accordingly. However, during runtime, the AE algorithm only reaches 66666 exposure at most,and the gain hits its upper limit at this point. Readings via V4L2 confirm that AE exposure reaches less than half of the configured upper limit.

LiMengYi_0-1786522788247.png

When manually configuring exposure via Live Control, the valid exposure can reach 150000,V4L2 exposure can also reach the upper limit.

We suspect this issue is related to RowTime. We modified the Row Time parameter inside AE Dister, but this change shows no visible effect; the auto exposure performance remains exactly the same as before.

We would like to know what adjustments are required to allow the AE algorithm to reach the configured maximum exposure under low-light conditions.

Re: IMX95 uGuzzi ISP : The AE algorithm can't achieve the maximum exposure

yipingwang — Mon, 17 Aug 2026 07:14:38 GMT

Based on the current behavior, the AE algorithm appears to be limited by the active sensor mode frame duration rather than by the absolute manual exposure capability. The value 66666 us corresponds to one frame at 15 fps. Therefore, even if the AE LIMITS maximum is set to 150000 us, AE will not be able to apply it unless the active sensor timing allows a frame period longer than 150 ms, or unless the driver/helper path extends VBLANK/frame length before programming exposure.

Please check whether the sensor driver exposes and correctly updates V4L2_CID_EXPOSURE, V4L2_CID_VBLANK, V4L2_CID_HBLANK, and V4L2_CID_PIXEL_RATE. For low-light AE to reach 150000 us, the active frame rate must be reduced to about 6.67 fps or lower, or the AE control path must dynamically increase VBLANK/frame length. Changing Row Time in AE Dister alone may not affect AE if the active exposure range reported through the V4L2/CameraHelper path remains capped at about 66666 us.

Please also confirm that the modified AE parameters are saved into the active DTP file referenced by config_ipa_uguzzi.yaml, copied to /usr/share/libcamera/ipa/nxp/neo/uguzzi/, and that the camera pipeline is restarted or the corresponding algorithm reconfiguration is applied. Live Control changes are generally temporary unless saved into the project/DTP or applied through the proper reconfiguration path.

My recommendation: treat this first as a frame-duration/VBLANK exposure-range issue, then verify DTP/profile activation. The fact that manual exposure reaches 150000 us is useful, but it does not prove the AE loop is allowed to request that value unless the AE-visible exposure range and frame timing are also updated.

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IMX95 uGuzzi ISP : The AE algorithm can't achieve the maximum exposure

Re: IMX95 uGuzzi ISP : The AE algorithm can't achieve the maximum exposure