[libcamera-devel] [PATCH v2 2/2] utils: raspberrypi: ctt: dng_load_image: Work with DNG files from Picamera2

[william.vinnicombe at raspberrypi.com]

From: William Vinnicombe <william.vinnicombe at raspberrypi.com>

The exif tags are different between raw files from libcamera-apps and
from Picamera2, causing issues loading data.

Add code to identify which tags are being used, and then load the
metadata from the correct tags.

Signed-off-by: William Vinnicombe <william.vinnicombe at raspberrypi.com>
Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
---
 utils/raspberrypi/ctt/ctt_image_load.py | 26 ++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/utils/raspberrypi/ctt/ctt_image_load.py b/utils/raspberrypi/ctt/ctt_image_load.py
index 934db123..29c17581 100644
--- a/utils/raspberrypi/ctt/ctt_image_load.py
+++ b/utils/raspberrypi/ctt/ctt_image_load.py
@@ -301,17 +301,29 @@ def dng_load_image(Cam, im_str):
         metadata.read()
 
         Img.ver = 100  # random value
-        Img.w = metadata['Exif.SubImage1.ImageWidth'].value
+        """
+        libcamera-apps create a separate Exif.Subimage1 for the picture
+        picamera2 stores everything under Exif.Image
+        this code detects which one is being used, and therefore extracts the correct values
+        """
+        try:
+            Img.w = metadata['Exif.SubImage1.ImageWidth'].value
+            subimage = "SubImage1"
+            photo = "Photo"
+        except KeyError:
+            Img.w = metadata['Exif.Image.ImageWidth'].value
+            subimage = "Image"
+            photo = "Image"
         Img.pad = 0
-        Img.h = metadata['Exif.SubImage1.ImageLength'].value
-        white = metadata['Exif.SubImage1.WhiteLevel'].value
+        Img.h = metadata[f'Exif.{subimage}.ImageLength'].value
+        white = metadata[f'Exif.{subimage}.WhiteLevel'].value
         Img.sigbits = int(white).bit_length()
         Img.fmt = (Img.sigbits - 4) // 2
-        Img.exposure = int(metadata['Exif.Photo.ExposureTime'].value*1000000)
-        Img.againQ8 = metadata['Exif.Photo.ISOSpeedRatings'].value*256/100
+        Img.exposure = int(metadata[f'Exif.{photo}.ExposureTime'].value*1000000)
+        Img.againQ8 = metadata[f'Exif.{photo}.ISOSpeedRatings'].value*256/100
         Img.againQ8_norm = Img.againQ8 / 256
         Img.camName = metadata['Exif.Image.Model'].value
-        Img.blacklevel = int(metadata['Exif.SubImage1.BlackLevel'].value[0])
+        Img.blacklevel = int(metadata[f'Exif.{subimage}.BlackLevel'].value[0])
         Img.blacklevel_16 = Img.blacklevel << (16 - Img.sigbits)
         bayer_case = {
             '0 1 1 2': (0, (0, 1, 2, 3)),
@@ -319,7 +331,7 @@ def dng_load_image(Cam, im_str):
             '2 1 1 0': (2, (3, 2, 1, 0)),
             '1 0 2 1': (3, (1, 0, 3, 2))
         }
-        cfa_pattern = metadata['Exif.SubImage1.CFAPattern'].value
+        cfa_pattern = metadata[f'Exif.{subimage}.CFAPattern'].value
         Img.pattern = bayer_case[cfa_pattern][0]
         Img.order = bayer_case[cfa_pattern][1]
 
-- 
2.25.1