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--- doc:appunti:hardware:sjcam-8pro-ambarella-firmware-modding [2022/06/09 15:57] – [What gamma curves are applied on each video mode] niccolo
+++ doc:appunti:hardware:sjcam-8pro-ambarella-firmware-modding [2022/06/15 14:41] – [White balance presets] niccolo
@@ Line 196: / Line 196: @@
 ^ Group      ^ Contained in file            ^ Used for video modes  ^
-| 4K30/*     | adj_video_default_00_Imx377  | 4K@(25,30)  |
+| 4K30/*      | adj_video_default_00_Imx377  | 4K@(25,30)  |
-| 4K60/*     | adj_video_default_01_Imx377  | 4K@(50,60)  |
+| 4K60/*      | adj_video_default_01_Imx377  | 4K@(50,60)  |
-| FHD60/*    | adj_video_default_02_Imx377  | 4K@24,\\ 4K-Ultra@(24,30)\\ 2720x1520@(24,25,30,50,60)\\ 2560x1440@(24,25,30,50,60)\\ 1920x1080@(24,25,30,50,60)\\ 1920x1080-Ultra@(30,60)\\ Touchscreen operations  |
+| FHD60/*     | adj_video_default_02_Imx377  | 4K@24,\\ 4K-Ultra@(24,30)\\ 2720x1520@(24,25,30,50,60)\\ 2560x1440@(24,25,30,50,60)\\ 1920x1080@(24,25,30,50,60)\\ 1920x1080-Ultra@(30,60)\\ Touchscreen operations  |
-| FHD120/*   | adj_video_default_03_Imx377  | 1920x1080@120  |
+| FHD120/*    | adj_video_default_03_Imx377  | 1920x1080@120  |
-| 720@240/*  | adj_video_default_04_Imx377  | 1280×720@240  |
+| 720@240/*   | adj_video_default_04_Imx377  | 1280×720@240  |
-| 4K30??/*   | adj_video_default_05_Imx377  | 4K@30 ISO 400, 1600, MAX-400 ??  |
+| 4K30Gyro/*  | adj_video_default_05_Imx377  | 4K@(25,30) with Gyro Stabilizer  |
 |                                                |||
 ^ Group           ^ Contained in file                 ^ Used for photo mode/ISO  ^
@@ Line 207: / Line 207: @@
 | Photo-Hi-ISO/*  | adj_hiso_still_default_00_Imx377  | Photo 800,1600,3200,6400\\ Photo Lapse 800,1600,3200,6400  |
-It is not clear when are used **adj_video_default_00_Imx377** and **adj_video_default_05_Imx377**. FIXME Need to check various 4K30 modes...
+It seems rather crazy, but the tables contained into **adj_video_default_05_Imx377** are used only when **Gyro Stabilizer** is enabled and mode is **4K** at **25** or **30** fps.
@@ Line 433: / Line 433: @@
 {{.:ambarella:bitrateeditor-wb-presets.png?direct&640|}}
+White balance is probably applied as a series of linear transformations to the **four raw values** captured by te **[[wp>Bayer_filter|Bayer filter sensor]]**. The four channels are **Red**, **Green-on-red**, **Blue** and **Green-on-blue**, each transformation consists of a multiplier coefficient (slope) and an offset.
+^ Gr  | Green on Red  |
+^ Gb  | Green on Blue  |
+^ Ya  | Y channel value of target image?  |
+^ Yb  | Y channel value of reference image?  |
 ===== 3D LUT tables =====