28 December 2007

Preparing photos for a digital picture frame

Challenge of the day was to fit as many photos as possible on a single flash card to stick in a digital photo frame. Here's how it's done.

The frame from Philips goes by the memorable name of 9FF2M4 , and by way of a quick review it is very nice. If I were a normal person, I would probably have copied the original 2.5MB / 5 megapixel images to the frame's flash card (1GB Compact Flash in this case, though it can take others), and put up with not being able to fit all the photos on, and having some of them show sideways. But being a perfectionist I instead sacrificed precious sleeping time to figure out what to do. In the end I managed to trim the files down to around 200KB each, and put portrait photos on a black background the right way up in order to save neck ache from squinting at a sideways eiffel tower. This was all done by the power of OSS and bash scripting. Here I present for your convenience the methods I used, and highlight some of the useful things I picked up along the way.

The first thing that taxed me was what size the photos needed to be to display best whilst taking up minimal space. You would think the answer would be emblazened on the product's box, but no! Philips don't seem to be too keen on promoting the resolution of the display, and even the shop keeper struggled to give me a number. The owner's manual states: "Resolution: 800 x 480 pixels (viewing area 680 x 480)" but after some time experimenting with test images created with the gimp I came to the conclusion that it was impossible to get the frame to display an image pixel perfect as it seemed to be re-scaling every picture regardless of original size. There appears to be no guidance from Philips as to what a good resolution for the photos would be, so after some experimentation I settled on 800x600 as this is slightly higher than the frame's native resolution, and fills the screen nicely without loosing too much off the edges when displayed.

The frame does not appear to read orientation from the exif data so I looked into rotating all the portrait images to display correctly. I am using the frame in its landscape orientation as that is the form of most of the photos, even though it can be placed in portrait orientation. When a portrait photos is displayed (eg 480x600), the frame puts a fair amount of the image off the top and bottom of the display, and by default puts it on a full white background which is a little hard on the eyes and detracts from darker photos. I therefore opted to create landscape images of 800x600 with a black background for all the portrait photos. I later discovered that you can on this frame change the background colour as follows: Main menu > Slideshow > Background colour > White / Black Grey.

The process I have used is a little specific to my setup and needs, but hopefully will give you a good starting point. I have created 3 bash scripts that call each other to orchestrate the conversion from my raw photo collection to a new set suitable for the frame, which in turn make use of imageMagick and exiftran to do the work.

I found out about imageMagick through searching, and tutorials such as HowTo - Batch Image Resize on Linux. The version packaged with Ubuntu 7.10 is quite old, so I ended up building and installing the latest version (6.3.7) from source to get all the functionality I needed.

exiftran is a nifty utility that reads the exif orientation information in a photo, losslessly rotates the photo to match and then updates the exif data. It is closely related to jpegtran.

My folder structure in my home folder (so the scripts make sense):
  • scripts (for bash scripts)
  • photos (originals)
    • 2005
      • 2005-12-31 event name
      • etc
    • 2006
    • etc
  • photos_frame (for the modified and shrunk photos which will be copied onto the flash card)
So without further ado, here's the scripts:

frame.sh - runs the processing scripts on each year folder of interest
#!/bin/bash -v
~/scripts/frame_photo_folder.sh 2005 ~/photos_frame/
~/scripts/frame_photo_folder.sh 2006 ~/photos_frame/
~/scripts/frame_photo_folder.sh 2007 ~/photos_frame/


frame_photo_folder.sh - runs the processing script on subfolder of the year
#!/bin/bash
#arg 1 = input folder
#arg 2 = output folder

INPUTPATH=$1
OUTPATH=$2
cd $INPUTPATH
if [ ! -d "$OUTPATH$INPUTPATH" ]
then
echo creating output folder \"$OUTPATH$INPUTPATH\"
mkdir $OUTPATH$INPUTPATH
fi
for fname in *
do
if [ -d "$fname" ]
then
if [ ! -d "$OUTPATH$INPUTPATH/$fname" ]
then
echo creating output folder \"$OUTPATH$INPUTPATH/$fname\"
mkdir "$OUTPATH$INPUTPATH/$fname"
fi
echo searching for jpg files in \"$fname\"
cd "$fname"
find . -maxdepth 1 -type f -name \*.JPG | xargs -iimgfile ~/scripts/frame_photo.sh "imgfile" "$OUTPATH$INPUTPATH/$fname"
cd ..
fi
done

frame_photo.sh
  • creates output folder(s)
  • copies original photo into output folder
  • uses exiftran to rotate the photo to the correct orientation
  • shrinks the photo to a maximum of 800x600, and fills any remaining space with a black background
#!/bin/bash

#arg 1 = photo file name
#arg 2 = where to put result
#resizes and pads suitable for a photo frame.

INPUTFILE=$1
OUTPATH=$2
#pwd
echo copying \"$INPUTFILE\" into \"$OUTPATH\"
cp "$INPUTFILE" "$OUTPATH"
cd "$OUTPATH"
#pwd
#echo processing \"$INPUTFILE\"
exiftran -ai "$INPUTFILE"
convert "$INPUTFILE" -resize '800x600>' -background black -gravity center -extent 800x600 "$INPUTFILE"


I timed the whole operation using the time command, and copied all output to a log file as follows.

$ time ./frame.sh 2>&1 | tee frame.log

The conversion of around 6000 photos took around one and a half hours.

The concept of redirection of stdout & stderr was neatly explained by the article CLI magic: need redirection?, so now I know that 2>&1 means redirect ouput number two into output number one, in other words redirect stderr into stdout, which then alows you to pipe the whole lot into something else like "tee" (No, not tea, though it may be interesting redirecting my photos into my tea...)

Add a comment or drop me a line if you find it interesting or useful or if you have any questions or criticisms.

Update:
I've worked this script into a small python gui app, check it out at http://github.com/timabell/photo-frame-prep

09 December 2007

Enabling TV-Out on Ubuntu Linux 7.10 on a Dell Inspiron 8500

This weekend, I finally got the tv-out working under linux (Ubuntu 7.10 aka gusty gibbon) on my laptop. Here's what was involved, including some of the (time consuming) red herrings involved in getting this set up.

I've included the full xorg.conf files for normal display and tv output at the end of this post.

I used the composite video output as that's what I have cables for. I haven't ever tried the s-video output, and I haven't tried the digital audio output since I divorced microsoft windows and threw her things out into the rain a couple of years ago.

The quality is pretty poor, but good enough. I think there's a limit of 800x600 for the video out. I'm getting a fair amount of interference on both the video and audio when the laptop is on mains and connected to my amplifier / tv. I'm not sure what the cause it but it's not bad enough to be unusable.

I installed the nvidia proprietary (that's a negative word in case you don't live in my world) drivers some time ago in order to get 3D acceleration, and I think this is a prerequisite to running the tv-out.

In my intial investigation I came across nvoption, which in theory allows you to turn on the tv-out on the nvidia cards. I did manage to compile and run it after several hours of trial, error and finding build dependencies but when I finally got it built and running I found that it would seg fault when I hit the "apply" button, hurrah! In the process of playing with nvoption however, I noticed the nv-online page that this person has very generously set up. Reading this it dawned on me that nvoption purely modifies the /etc/X11/xorg.conf file, and that I don't actually need the tool to get tv-out running. I had originally presumed (the brother of all ...) that the nvoption tool did some magical proprietary prodding of the graphics card directly. After a bit of searching to find out where the options should go (the device section), I was then able to use the documentation of options in the second frame of the nv-online page to configure my own X. After a bit of experimenting with different options and lots of restarting of the X server (ctrl+alt+backspace) I was able to get the desired result of the display mirrored/cloned on both the lcd and the television.

I tried the nvidia-settings gui tool that comes with the proprietary drivers, but it was no use for this task. This tool modifies the xorg.conf file. It did help me recently with a normal dual screen setup (using a crt monitor plugged into the vga port on the laptop), but it was no help for the tv-out, which was not even mentioned in the interface.

There is a tool called displayconfig-gtk which is fairly new to Ubuntu that allows you to save named display profiles for different configurations (including dual screen, though it didn't quite behave for me). It can be found under System > Administration > Screens and Graphics. This stores an xorg.conf file for each profile in /var/lib/displayconfig-gtk/locations/, and an index file in /var/lib/displayconfig-gtk/locations.conf. This is almost ideal, as I have created a set of xorg.conf files for my various setups, however it doesn't seem to cope with applying these custom xorg files. Additionally nvidia seem to have a weird way of setting the screen to run at its native resolution of 1920x1600, and this tool doesn't cope with it. This was corrected by selecting the right resolution under System > Preferences > Screen Resolution.

Sadly it looks like there are no tools for easy switching X configuration files, so the process for now is involves manually copying the config files. I've created multiple files in /etc/X11, one for each set up including xorg.conf_lcd and xorg.conf_tv. The switching process is then something along the lines of "cd /etc/X11/", "sudo cp xorg.conf_tv xorg.conf", ctrl+alt+backspace (restart x server).

If it's any consolation I recall the process in windows involved starting from scratch in a distinctly non-intuitive gui and trying to get a whole load of settings just right, so being able to save the settings is a big step up. I think it took similar amounts of time to get tv-out running under windoze. I guess that's the price we pay for allowing companies to deny us access to the hardware specs so it can be integrated properly. I bought this laptop before I knew how much control I was giving away, and I endeavour not to make such mistakes these days.

The "designed for windows xp" sticker has been moved to the equally shiny microwave oven which brings me a small piece of joy when I make porridge in the morning.



xorg.conf for just the laptop screen
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 1.0 (buildmeister@builder3) Mon Apr 16 20:38:05 PDT 2007

Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Inputdevice "Synaptics Touchpad"
EndSection

Section "Files"
RgbPath "/usr/X11R6/lib/X11/rgb"
EndSection

Section "Module"
Load "dbe"
Load "extmod"
Load "type1"
Load "freetype"
Load "glx"
EndSection

Section "ServerFlags"
Option "Xinerama" "0"
EndSection

Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
Identifier "Synaptics Touchpad"
Driver "synaptics"
Option "SendCoreEvents" "true"
Option "Device" "/dev/psaux"
Option "Protocol" "auto-dev"
Option "HorizScrollDelta" "0"
EndSection

Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection

Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Sharp"
HorizSync 30.0 - 75.0
VertRefresh 60.0
Option "DPMS"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce4 4200 Go"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
Option "metamodes" "DFP: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
Modes "1600x1200" "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
EndSection




xorg.conf for running the tv-out at 800x600, with the laptop displaying the same
# nvidia-settings: X configuration file generated by nvidia-settings
# nvidia-settings: version 1.0 (buildmeister@builder3) Mon Apr 16 20:38:05 PDT 2007

Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
InputDevice "Mouse0" "CorePointer"
Inputdevice "Synaptics Touchpad"
EndSection

Section "Files"
RgbPath "/usr/X11R6/lib/X11/rgb"
EndSection

Section "Module"
Load "dbe"
Load "extmod"
Load "type1"
Load "freetype"
Load "glx"
EndSection

Section "ServerFlags"
Option "Xinerama" "0"
EndSection

Section "InputDevice"
# generated from default
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/psaux"
Option "Emulate3Buttons" "no"
Option "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
Identifier "Synaptics Touchpad"
Driver "synaptics"
Option "SendCoreEvents" "true"
Option "Device" "/dev/psaux"
Option "Protocol" "auto-dev"
Option "HorizScrollDelta" "0"
EndSection

Section "InputDevice"
# generated from default
Identifier "Keyboard0"
Driver "kbd"
EndSection

Section "Monitor"
# HorizSync source: edid, VertRefresh source: edid
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Sharp"
HorizSync 30.0 - 75.0
VertRefresh 60.0
Option "DPMS"
EndSection

Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BoardName "GeForce4 4200 Go"
Option "TwinView" "1"
Option "TwinViewOrientation" "Clone"
Option "MetaModes" "800x600, 800x600;"
Option "TVStandard" "PAL-I"
Option "ConnectedMonitor" "DFP,TV"

EndSection

Section "Screen"
Identifier "Screen0"
Device "Videocard0"
Monitor "Monitor0"
DefaultDepth 24
#Option "metamodes" "DFP: nvidia-auto-select +0+0"
SubSection "Display"
Depth 24
Modes "1600x1200" "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
EndSection