Command Line Interface ~ Linux

Notes to self:  A few useful image processing commands for running in Linux.  All these are much faster to run from the CLI than using an app that having to manage graphics at the same time. -

convert *.jpg -average <averaged-filename>.jpg – averaging command

convert *.jpg -evaluate-sequence median <output file-name>.jpg  - a different averaging command

mogrify -resize 1920 *.jpg – resizing command

mogrify -bordercolor black -border 10x10 *.jpg – adding a thin black edge to images

mogrify -bordercolor white -border 400x400 *.jpg – adding a white border to images

convert <filename>.<file-extension> -colorspace gray <output filename>.<file-extension> – command to convert a single image to black and white

for i in *.jpg; do convert "$i" -colorspace Gray  "BW_$i"; done – Bash script to convert a bunch of files into black and white

exiftool -a -u -s -G1 <file_name> - to read EXIF image file data

gmic -input <filename.file-extension> scale_dcci2x , cut 0,255 round output <theOutputFileName>.tif - command to perform a DCCI2x upsize

 

Digital Zone System ~ Validation Testing

I wanted to prove to myself something about a Digital Zone System that I've been working on.  

What I wanted to prove was that once I'd set up an input correction curve for each camera I own that the result would match the output of my other cameras, each with their own unique input correction curve.

The cameras I own span recent digital sensor development and manufacturing.  For this validation I chose two different formats, two different megapixel counts, and three different years sensor implementations.

In each case I spot metered the light area to Zone 7 and let the shadows fall where they will.  I did this because in digital I meter for the highlights and process for the shadows.  Keeping in mind, of course, this is the exact opposite of what we do with film.

Here's what I see ->

 

 

To my eyes this is an excellent match. Each input correction curve accurately matches the 1EV step as described by the original Zone System and adapted here to digital.

So here's a little game.  Want to win a free beer?  Tell me which camera made which image.

For me that's an easy bet for the house.  I seriously doubt anyone will be able to pass this test.  In fact, it's rather irrelevant.  Though it does make the point that if we understand our tools and set up our processing environments correctly, manufacturer to manufacturer variations, sensor to sensor variations, and generation to generation developments can all be "leveled" to the point good image making doesn't depend on tools as much as some would have us believe.