Working with raw image data
From ElphelWiki
Downloading
- Available options (channels can be 0..3):
# set receiving buffer size in 4kB pages (thus 4096 equals to 16MB) echo {size} > /sys/devices/soc0/elphel393-mem\@0/buffer_pages_raw_chn2 # start from the N-th frame position in buffer. Currently, 0 or 1 echo 1 > /sys/devices/soc0/elphel393-videomem\@0/video_frame_number # initiate transfer, wait for X-th frame (X - absolute frame number), 0 = no waiting echo X > /sys/devices/soc0/elphel393-videomem\@0/membridge_start2 # copy to file cat /dev/image_raw2 > /tmp/test.raw # see in hex hexdump /tmp/test.raw # copy to PC scp /tmp/test.raw user@address:/path/
- Minimal:
echo 4096 > /sys/devices/soc0/elphel393-mem\@0/buffer_pages_raw_chn2 echo 0 > /sys/devices/soc0/elphel393-videomem\@0/membridge_start2 cat /dev/image_raw2 > /tmp/test.raw
Displaying
ImageMagick
- Camera settings: 2592x1936 JPEG, actual valid pixels - 2596x1940, pixels read - 2608x1940:
convert -size 2608x1940 -depth 8 -endian MSB -normalize gray:test.raw -compress lzw result.tiff
- Camera settings: 2592x1936 JP4, actual pixels available: 2592x1936
convert -size 2592x1936 -depth 8 -endian MSB -normalize gray:test.raw -compress lzw result.tiff
The result is a grayscale tiff
bayer2rgb program
- Available here.
- Camera settings: 2592x1936 JPEG:
bayer2rgb -w 2608 -v 1940 -b 8 -f GRBG -m AHD -t -i test.raw -o test.tiff
The result is a colored tiff image. Pixel values are linear.
Python
- Camera settings: 2592x1936 JPEG:
- a)
#!/usr/bin/env python import cv2 import numpy as np width = 2608 height = 1940 with open("test.raw", "rb") as rawimg: img = np.fromfile(rawimg, np.dtype('u1'), width * height).reshape(height, width) img.tofile("test2.raw") colimg = cv2.cvtColor(img, cv2.COLOR_BAYER_GB2BGR) cv2.imwrite("test.jpeg", colimg) #cv2.imshow("color", colimg) #cv2.waitKey(0)
- b) PC:
#!/usr/bin/python3 from PIL import Image rawData = open("test.raw", 'rb').read() imgSize = (2608,1940)# the image size img = Image.frombytes('L', imgSize, rawData) img.save("result.jpeg")# can give any format you like .png
The result will be a grayscale image.
Processing
Open the file and process as pixel array RGGB, GRBG, GBRG or BGGR - 8 or 16 bits