Difference between revisions of "Working with raw image data"

Revision as of 11:09, 18 January 2018

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