TL;dr

I have average colour of my photos arranged chronologically January 1, 20219 - December 31, 2020. It may be wrong, need to double check :-) This is the output of photoshop in interleaved mode, 3 channels (R, G, B)

Extra Bonus “glitch” art

when you don’t use interleave mode in Photoshop

Details

05april2021 still not sure why imagemagick doesn’t work, maybe because the header is missing or maybe because it doesn’t end with ‘.raw’?

add the header as per this stack overflow question, Converting raw images without headers?
```
{ printf "P6\n%d %d\n255\n" WIDTH HEIGHT ; cat YOURFILE; } > result.ppm
```

or use ffmpeg as per this stack overflow question, Convert raw RGB32 file to JPEG or PNG using FFmpeg?

ffmpeg -f rawvideo -pixel_format rgba -video_size 320x240 -i input.raw output.png #i would use rgb instead of rgba

05april2021 the file has to be called .raw to be opened in photoshop in interleaved mode

renamed 2020-and-2019-roland-flickr-imagemagick-average-colours.rgb to: 2020-and-2019-roland-flickr-imagemagick-average-colours.raw and opened in photoshop in interleaved mode, 3 channels, 222x222pixels and it worked!
here is the PNG which worked: https://github.com/rtanglao/rt-flickr-sqlite-csv/blob/main/THUMBS_75X75/interlaced-2020-and-2019-roland-flickr-imagemagick-average-colours.png
if you select non interleaved mode, then it doesn’t work but you get glorious glitch art: https://github.com/rtanglao/rt-flickr-sqlite-csv/blob/main/THUMBS_75X75/2020-and-2019-roland-flickr-imagemagick-average-colours.png

03april2021 hilariously gnuplot works

see http://gnuplot.sourceforge.net/demo_4.4/image.1.gnu which is an example from: http://gnuplot.sourceforge.net/demo_4.4/image.html

plot '2020-and-2019-roland-flickr-imagemagick-average-colours.rgb' binary array=222x222 flipy format='%uchar' with rgbimage

output: https://github.com/rtanglao/rt-flickr-sqlite-csv/blob/main/THUMBS_75X75/gnuplot-2020-and-2019.png

03april2021 create file of colours and then raw file and then png

1. remove the one bad file which has synth_75sqisvalid set to 0 aka false

mlr --csv cut -f synth_75imaveragecolour,synth_75sqisvalid \
../../files_too_big_for_github_rt-flickr-sqlite-csv/2020-and-2019-roland-flickr-filename-imagemagick-avg-colour-metadata.csv\
| grep -v ",0" | wc -l
49549
mlr --csv cut -f synth_75imaveragecolour,synth_75sqisvalid \
../../files_too_big_for_github_rt-flickr-sqlite-csv/2020-and-2019-roland-flickr-filename-imagemagick-avg-colour-metadata.csv\
> 2020-and-2019-roland-flickr-imagemagick-average-colours.csv
mlr --csv cut -f synth_75imaveragecolour \
>  2020-and-2019-roland-flickr-imagemagick-average-colours.csv\
>  | tail -n +2 >2020-and-2019-roland-flickr-imagemagick-average-colours.txt

2. create raw file

#xxd -r -p 2020-and-2019-roland-flickr-imagemagick-average-colours.txt \
2020-and-2019-roland-flickr-imagemagick-average-colours.rgb
# 222 x 222 = 49284
xxd -l 49284 -u -r -p \
2020-and-2019-roland-flickr-imagemagick-average-colours.txt 2020-and-2019-roland-flickr-imagemagick-average-colours.rgb

3. create png

square root of 49549 is approximately 222

magick convert -depth 8  -size 222x222 2020-and-2019-roland-flickr-imagemagick-average-colours.rgb\
 2020-and-2019-roland-flickr-imagemagick-average-colours.png

fails on ubuntu 20.04 with convert and on macOS catalina with magick:

convert -size 222x222 -depth 8 RGB:2020-and-2019-roland-flickr-imagemagick-average-colours.rgb image.png
convert-im6.q16: unexpected end-of-file `2020-and-2019-roland-flickr-imagemagick-average-colours.rgb': No such file or directory @ error/rgb.c/ReadRGBImage/242.
convert-im6.q16: no images defined `image.png' @ error/convert.c/ConvertImageCommand/3258.

03april2021 imagemagick average colour worked?!?

roland@Rolands-MacBook-Air THUMBS_75X75 % bundle exec ../get-filename-imagemagick-average-colour-from-75x75thumbnail.rb \
../../files_too_big_for_github_rt-flickr-sqlite-csv/2020-and-2019-roland-flickr-metadata.csv \
../../files_too_big_for_github_rt-flickr-sqlite-csv/2020-and-2019-roland-flickr-filename-imagemagick-avg-colour-metadata.csv

03april2021 current plan

I don’t trust myself :-) to take the 100% care needed to get csvjoin to work, it’s easy to mess up
so i will add the column from ruby and in fact have multiple columns
- synth_75sqfilename (the filename of the 75x75 thumbnail)
- synth_75imaveragecolour (average colour by resizing to 1x1 in imagemagick)
- synth_75sqisvalid (in case the thumbnail is not a valid jpeg or png), 1 = valid, 0 = invalid (there’s only 1 invalid 75x75px thumbnail from all 45000 2019-2020 photos

03april2021 csvjoin does add columns like i want

roland@Rolands-MacBook-Air THUMBS_75X75 % cat testcsv.csv 
column1
samplecolumn1value
roland@Rolands-MacBook-Air THUMBS_75X75 % cat column2.csv 
column2
samplecolumn2value
roland@Rolands-MacBook-Air THUMBS_75X75 % csvjoin testcsv.csv column2.csv
column1,column2
samplecolumn1value,samplecolumn2value