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Exif Metadata from Raspberry Pi Camera Problem...

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Exif Metadata from Raspberry Pi Camera Problem...

Posted: 2015-01-28T11:17:25-07:00
by Andros
Hi all,

I am newbie here, but I need your help. Actually I am using exiftool to extract exif data from some images created with Raspberry Pi camera. Here is my output from exiftool:

Code: Select all

root@raspi /usr/freeware # time exiftool /tmp/snapshot.tmp.jpg
ExifTool Version Number         : 8.60
File Name                       : snapshot.tmp.jpg
Directory                       : /tmp
File Size                       : 107 kB
File Modification Date/Time     : 2015:01:28 19:30:05+02:00
File Permissions                : rw-r--r--
File Type                       : JPEG
MIME Type                       : image/jpeg
Exif Byte Order                 : Big-endian (Motorola, MM)
Make                            : RaspberryPi
Camera Model Name               : RP_OV5647
X Resolution                    : 72
Y Resolution                    : 72
Resolution Unit                 : inches
Modify Date                     : 2015:01:28 19:30:04
Y Cb Cr Positioning             : Centered
Exposure Time                   : 0.7
F Number                        : 2.9
Exposure Program                : Aperture-priority AE
ISO                             : 400
Exif Version                    : 0220
Date/Time Original              : 2015:01:28 19:30:04
Create Date                     : 2015:01:28 19:30:04
Components Configuration        : Y, Cb, Cr, -
Shutter Speed Value             : 0.7
Aperture Value                  : 2.9
Brightness Value                : 0
Max Aperture Value              : 2.9
Metering Mode                   : Other
Flash                           : No Flash
Focal Length                    : 3.6 mm
Maker Note Unknown Text         : (Binary data 313 bytes, use -b option to extract)
Flashpix Version                : 0100
Color Space                     : sRGB
Exif Image Width                : 1920
Exif Image Height               : 1440
Interoperability Index          : R98 - DCF basic file (sRGB)
Exposure Mode                   : Auto
White Balance                   : Auto
Compression                     : JPEG (old-style)
Thumbnail Offset                : 1032
Thumbnail Length                : 24576
Image Width                     : 1920
Image Height                    : 1440
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
Aperture                        : 2.9
Image Size                      : 1920x1440
Shutter Speed                   : 0.7
Thumbnail Image                 : (Binary data 24576 bytes, use -b option to extract)
Focal Length                    : 3.6 mm
Light Value                     : 1.5

real    0m8.161s
user    0m3.910s
sys     0m0.080s
The problem with this tool (exiftool) is that is extremely slow especially if you are run it from a Raspberry Pi, So I decided to turn to imagemagick identify but unfortunately I cannot find "Light Value" data as before. Even if I run identify -verbose I cannot find such similar value in any field. Any idea how can I find or calculate it?

You can always take an image from my Raspberry Pi camera from: http://users.otenet.gr/~kcr58/snapshot.jpg

Thanks for your time.

Code: Select all

root@raspi /usr/freeware # identify -verbose /tmp/snapshot.tmp.jpg

Image: /tmp/snapshot.tmp.jpg
  Format: JPEG (Joint Photographic Experts Group JFIF format)
  Class: DirectClass
  Geometry: 1920x1440+0+0
  Resolution: 72x72
  Print size: 26.6667x20
  Units: PixelsPerInch
  Type: TrueColor
  Endianess: Undefined
  Colorspace: sRGB
  Depth: 8-bit
  Channel depth:
    red: 8-bit
    green: 8-bit
    blue: 8-bit
  Channel statistics:
    Red:
      min: 0 (0)
      max: 255 (1)
      mean: 11.8298 (0.0463913)
      standard deviation: 26.7468 (0.104889)
      kurtosis: 46.5051
      skewness: 6.27543
    Green:
      min: 0 (0)
      max: 255 (1)
      mean: 10.2748 (0.0402935)
      standard deviation: 24.5483 (0.0962677)
      kurtosis: 56.2607
      skewness: 6.89832
    Blue:
      min: 0 (0)
      max: 255 (1)
      mean: 4.20187 (0.0164779)
      standard deviation: 17.7321 (0.0695376)
      kurtosis: 99.0793
      skewness: 9.06196
  Image statistics:
    Overall:
      min: 0 (0)
      max: 255 (1)
      mean: 8.76883 (0.0343876)
      standard deviation: 23.3269 (0.0914781)
      kurtosis: 62.5181
      skewness: 7.2892
  Rendering intent: Perceptual
  Gamma: 0.454545
  Chromaticity:
    red primary: (0.64,0.33)
    green primary: (0.3,0.6)
    blue primary: (0.15,0.06)
    white point: (0.3127,0.329)
  Interlace: None
  Background color: white
  Border color: srgb(223,223,223)
  Matte color: grey74
  Transparent color: black
  Compose: Over
  Page geometry: 1920x1440+0+0
  Dispose: Undefined
  Iterations: 0
  Compression: JPEG
  Quality: 61
  Orientation: Undefined
  Properties:
    date:create: 2015-01-28T20:08:05+02:00
    date:modify: 2015-01-28T20:08:05+02:00
    exif:ApertureValue: 30705/10000
    exif:BrightnessValue: 0/100
    exif:ColorSpace: 1
    exif:ComponentsConfiguration: 1, 2, 3, 0
    exif:Compression: 6
    exif:DateTime: 2015:01:28 20:08:04
    exif:DateTimeDigitized: 2015:01:28 20:08:04
    exif:DateTimeOriginal: 2015:01:28 20:08:04
    exif:ExifImageLength: 1440
    exif:ExifImageWidth: 1920
    exif:ExifOffset: 192
    exif:ExifVersion: 48, 50, 50, 48
    exif:ExposureMode: 0
    exif:ExposureProgram: 3
    exif:ExposureTime: 738814/1000000
    exif:Flash: 0
    exif:FlashPixVersion: 48, 49, 48, 48
    exif:FNumber: 28984/10000
    exif:FocalLength: 35976/10000
    exif:ImageLength: 1440
    exif:ImageWidth: 1920
    exif:InteroperabilityIndex: R98
    exif:InteroperabilityOffset: 884
    exif:ISOSpeedRatings: 400
    exif:JPEGInterchangeFormat: 1020
    exif:JPEGInterchangeFormatLength: 24576
    exif:Make: RaspberryPi
    exif:MakerNote: 101, 118, 61, 45, 49, 32, 109, 108, 117, 120, 61, 45, 49, 32, 101, 120, 112, 61, 55, 51, 56, 56, 49, 52, 32, 97, 103, 61, 49, 48, 50, 52, 32, 102, 111, 99, 117, 115, 61, 50, 53, 53, 32, 103, 97, 105, 110, 95, 114, 61, 49, 46, 48, 48, 48, 32, 103, 97, 105, 110, 95, 98, 61, 49, 46, 48, 48, 48, 32, 103, 114, 101, 101, 110, 110, 101, 115, 115, 61, 48, 32, 99, 99, 109, 61, 48, 44, 48, 44, 48, 44, 48, 44, 48, 44, 48, 44, 48, 44, 48, 44, 48, 44, 48, 44, 48, 44, 48, 32, 109, 100, 61, 50, 32, 116, 103, 61, 55, 49, 50, 51, 32, 55, 49, 50, 51, 32, 111, 116, 104, 61, 48, 32, 48, 32, 98, 61, 48, 32, 102, 61, 55, 49, 50, 51, 32, 55, 49, 50, 51, 32, 102, 105, 61, 48, 32, 73, 83, 80, 32, 66, 117, 105, 108, 100, 32, 68, 97, 116, 101, 58, 32, 74, 97, 110, 32, 49, 52, 32, 50, 48, 49, 53, 44, 32, 49, 57, 58, 52, 54, 58, 50, 52, 32, 86, 67, 95, 66, 85, 73, 76, 68, 95, 73, 68, 95, 86, 69, 82, 83, 73, 79, 78, 58, 32, 56, 51, 52, 49, 56, 101, 98, 48, 51, 53, 98, 56, 99, 98, 55, 54, 50, 101, 55, 100, 49, 98, 102, 53, 102, 98, 49, 48, 99, 48, 57, 101, 99, 102, 50, 53, 56, 97, 48, 52, 32, 40, 99, 108, 101, 97, 110, 41, 32, 86, 67, 95, 66, 85, 73, 76, 68, 95, 73, 68, 95, 85, 83, 69, 82, 58, 32, 100, 99, 52, 32, 86, 67, 95, 66, 85, 73, 76, 68, 95, 73, 68, 95, 66, 82, 65, 78, 67, 72, 58, 32, 109, 97, 115, 116, 101, 114, 32
    exif:MaxApertureValue: 30705/10000
    exif:MeteringMode: 255
    exif:Model: RP_OV5647
    exif:ResolutionUnit: 2
    exif:ShutterSpeedValue: 436716/1000000
    exif:WhiteBalance: 0
    exif:XResolution: 72/1
    exif:YCbCrPositioning: 1
    exif:YResolution: 72/1
    jpeg:colorspace: 2
    jpeg:sampling-factor: 2x2,1x1,1x1
    signature: dcc063eaf5dadf9ce635394ab91e1abff08c1b482c49b8c0345d7f54eb5139b8
  Profiles:
    Profile-exif: 25602 bytes
  Artifacts:
    filename: /tmp/snapshot.tmp.jpg
    verbose: true
  Tainted: False
  Filesize: 109KB
  Number pixels: 2.765M
  Pixels per second: 1.562MB
  User time: 0.870u
  Elapsed time: 0:02.769
  Version: ImageMagick 6.7.7-10 2014-04-09 Q16 http://www.imagemagick.org

Re: Exif Metadata from Raspberry Pi Camera Problem...

Posted: 2015-01-28T16:45:48-07:00
by magick
The light value is a calculated value: log2 (f-number^2 / shutter speed / ISO/100). We don't calculate it, but you can from the EXIF metadata.

Re: Exif Metadata from Raspberry Pi Camera Problem...

Posted: 2015-01-28T19:26:08-07:00
by Andros
Thanks a lot guys. Anyway I wrote a bash script that can do this calculation automatically:

Code: Select all

#!/bin/bash

ALL=( `identify -format "%[EXIF:FNumber] %[EXIF:ShutterSpeedValue] %[EXIF:ISOSpeedRatings]" $1` )

ALL=( `convert xc: -format "%[fx:${ALL[0]}] 1/%[fx:floor(pow(2,${ALL[1]}))]" info:` ${ALL[2]} )

echo "l((( ${ALL[0]} ) ^ 2) / (${ALL[1]}) / (${ALL[2]} / 100) ) / l(2)" | bc -l
Just run this script with your .jpg as argument:

Code: Select all

# script snapshot.jpg
13.84941189781605230136

#
And as I expect, is far away faster than to run exiftool. Enjoy :)
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