Workflow (3) – quick RAW converting batch

Welcome back!

After covering the general concept of workflow and talking about the RAW vs JPEG dispute, we realize that after a day shooting, we will probably end up with:

1. a mix of RAW and JPEG files
2. the need to process these images quickly for review

Now this is not about fine-tuned post-processing of 4 images, this is about “I have 500 files in a directory, of which 150 are RAW and the rest JPEG. I want to browse through these files and check which ones I keep and which ones I throw away”.

My camera does it this way: JPEG files are numbered _igpXXXX.jpg and RAW fils are numbered imgpXXXX.pef. PEF is the Pentax RAW file extension and XXXX is the file number. So I would need a file viewer that allows me to view PEF and JPG files and sort them by time taken (in the EXIF datas). Or, Linux being what it is, I would need a trick.

The trick

The idea here is to quickly convert all the RAW files to JPEG and rename them to fit the JPEG pattern – with _r.jpg at the end so we know we have a RAW version of this file available. Then we can review all our files in a standard image viewer (my favorite is Gthumb):

• they are all JPEG
• they all follow the same naming pattern (so order by name also means order by order the pictures were taken)
• we can identify (_igpXXXX_r.jpg) the files for which we have a RAW version.

In order to achieve this, we need: a copy of ufraw and a batch script.

Ufraw a RAW converter for Linux…

We will talk more in detail about Ufraw (web, wiki) later, but let’s just say that it is a Linux RAW converter that offers

• one picture conversion / editing user interface
• a command line interface.

It is the command line interface that we are interested in here. So entering something like:

ufraw-batch mypicture.pef –output mypicture.jpg

on a terminal from the directory where mypicture.pef is would convert my RAW file and spit out mypicture.jpg (white keeping the original file, obviously). You can specify quite a few parameters.

… and a batch file

Now consider this batch file:

#!/bin/bash

if [ ! -d ./processed_images ]; then mkdir ./processed_images; fi;

# processes raw files
for f in *.pef;
do
	echo "Processing $f"
	ufraw-batch \
		--wb=camera \
		--exposure=auto \
		--out-type=jpeg \
		--compression=96 \
		--out-path=./processed_images \
		$f
done

cd ./processed_images

# change the image names
for i in *.jpg;
do
	mv "$i" "${i/.jpg}"_r.jpg;
done
for i in *.jpg;
do
	mv "$i" "${i/imgp/_igp}";
done

What it does is take each *.pef file (my RAW files) and convert them to JPEG, using the in camera white balance, auto exposure and a 96% JPEG compression (roughly equivalent to the size I get from the camera). It saves the image in a subfolder (processed_images) and then changes the image names to fit the JPEG pattern (except for the _r marker at the end).

In order to use this thing, just copy and paste it to a text file. Save the file as raw-processing.sh and make it executable (usually there is a choice in your file manager). Then copy and paste the file to the directory where your images are and execute it – either by clicking on it, or by opening a terminal in the directory and typing ./raw-processing.sh at the command prompt. Obviously, this only works for Pentax PEF files and you need to have a working copy of Ufraw.

So what is that all about?

What we made today is just an equivalent to the in-camera processing from RAW to JPEG. That allows us to consider all our files as standard JPEG (which we can easily browse, review and sort out – ie, throw away…). But we keep our RAW files and their post-processing power at hand, so if we stumble upon a portfolio-grade image (and that we shoot that one in RAW), we can go back to it for fine-tuned post-processing.

And the interest of that is that it requires no post-processing time. Just start your batch script, make yourself a cup of coffee (drink it, depending on how many files you need to process…) and you can start reviewing your files. No attention needed to fine-tune each file (not interesting at that time). Just a quick, easy and standard way to review all your files.

I think Linux for photography not there yet (otherwise, there wouldn’t be a need for this blog 🙂 ). However, this forces us to manage and find our way – and all in all, I think tricks like this one are not just workarounds: to me, this perfectly fits the bill for easily dealing with a big number RAW files when back from a day of shooting.

Here is one more picture which I like a lot – it was pitch dark (wedding dancing time) and almost no chance to take good pictures, but then the accordionist / singer just moved a step forward in the light, time to franticly shoot a couple of pictures before she moved again… and guess what? It is based on a JPEG file.