Jeff Epler's blog

24 July 2009, 2:19 UTCCropGUI 0.1.1: now with gtk


Gtk version of cropgui

Earlier this year, I released a program for lossless cropping of jpeg images. This week, based on feedback from Ingrid, I ported the program to gtk (it originally used tkinter).

24 February 2009, 23:09 UTCcropgui: A Linux GUI for Lossless JPEG Cropping


Cropping a tiny insect

Update: See the newer version of cropgui

Of the pictures from my recent trip I'd like to put online, I've found that in 75% of the cases where I want to retouch the photo, it's to crop it and nothing else. Since I shoot in jpeg, it's a lossy process to load the jpeg in gimp, crop it, and write the result.

But it turns out that debian's jpegtran has a "-crop" flag which performs lossless cropping of jpeg images as long as the crop is to a multiple of what the manpage calls the "iMCU boundary", a (usually?) 8x8 block of pixels. This feature was pioneered by Guido of jpegclub.org some years ago.

There's apparently a nice Windows front-end to this program, but I didn't find a Linux one. So I wrote one! It's pretty basic, but it gets the job done. You can download it below.

14 February 2009, 16:24 UTCCanon Digital Rebel XSi (450D) on Linux Ubuntu Hardy 8.04


ufraw-converted image	(M) (L)

gimp-ufraw (ubuntu hardy) would open cr2 files from my new camera (Canon Digital Rebel XSi, aka 450D), but until I applied a patch the colors were all wrong. (This is on launchpad but not fixed in an official ubuntu package yet)

Another nice tool with this camera is gphotofs, which allows the camera to be mounted as a filesystem even though it uses PTP rather than mass storage. The one packaged for Ubuntu Hardy works nicely.

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17 November 2008, 15:16 UTCXO-1 screen simulation


olpcgui.py in action

I failed to resist the new G1G1 program and ordered myself an XO-1 today. As a lot of geeks are, I'm intrigued by the screen. Updated: sped up the simulation a bit with a pyrex module.

15 August 2008, 2:59 UTCCairo-based waveform demo


Image generated by waveform demo

It's late, but I just wanted to toss this online. It's a Python / Cairo / Gtk based waveform viewer. Maybe it will become the foundation for a replacement for both emc2's halscope and the sump.org logic analyzer GUI, when I find a hundred hours or so to work on it.

The main feature is that when a trace has more than one sample per horizontal pixel it goes into a sort of "envelope" mode, with a fainter trace showing the min and max and the bright trace following the median (not mean) value.

The demo writes out 3 static pngs, then shows a window that you can re-size to get an idea of the responsiveness. I have only run on a very beefy machine so far, which gives the impression that all is well. Resizing is tolerable, and exposing (and, by analogy, scrolling, when I get around to it) is pretty responsive.

Files currently attached to this page:

demo.py

7.0kB

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26 November 2007, 19:29 UTCMaking a YouTube video of X program
Instructions for recording any X program into a video suitable for upload to youtube

23 October 2006, 18:15 UTCThe Bayer sensor vs the Foveon sensor (part 2 of 2)


cactus	(M) (L)

In this part of the article, I present the images and compare the results to my predictions.

23 October 2006, 2:16 UTCThe Bayer sensor vs the Foveon sensor (part 1 of 2)
Using synthetic images, I have subjectively compared the effective resolution of a Bayer and a Foveon sensor with the same number of photosites.

31 August 2006, 19:52 UTCTired of missing OpenGL manpages on Ubuntu
For whatever reason, there are no OpenGL manpages on Ubuntu. So I took the set of manpages from my Fedora Core machine, specifically from the xorg-x11-devel package. Untar in the root directory, then "man glBitmap" will work.

Update, 20090729: added debian packaging. Untarring in / is so gross. Instead, 'sudo apt-get install manpages-opengl_0_all.deb'.

Files currently attached to this page:

manpages-opengl_0.dsc	475 bytes
manpages-opengl_0.tar.gz	343.1kB
manpages-opengl_0_all.deb	350.5kB
vismach-alex2.patch	682 bytes

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29 April 2006, 21:58 UTC in softwareOnscreen Crosshairs in tcl/tk
I was staring too long at a screenshot of a graph on some web page, wishing I could tell if two things lined up. Well, inspiration struck, and this program was born. Two windows—one that is one pixel wide, and another that is one pixel tall—are created, and they follow the mouse around every 1/10 second or so. They're displaced by one pixel so that clicking will hit the underlying window, not the crosshair.

I apologize for the changing colors, since xor isn't available with this simple method of drawing the lines, it's the only way to be sure to get contrast. I considered making the color depend on e.g., whether SHIFT is pressed, but if Tk provides this information to a window that doesn't have focus, I overlooked it in the manpages.

27 November 2005, 21:38 UTC in softwareStippler 1.0 source release
21 November 2005, 17:54 UTC in softwareHershey Vector Fonts
7 November 2005, 19:12 UTCTwo optical illusions
9 October 2005, 18:23 UTCQOOP -- the final chapter?
3 October 2005, 23:28 UTCResponse from QOOP (updated with comparison images)
30 September 2005, 13:44 UTCQOOP: My friends' reaction to one of their photo books
11 September 2005, 18:15 UTC in softwareglif: generate client-side gif files from javascript
7 September 2005, 2:55 UTCFlicker and QOOP
5 June 2005, 2:30 UTCa plug for Eagle3D
26 May 2005, 0:36 UTC in projectsXY display update
9 May 2005, 1:58 UTC in softwarevgaxy -- create XY scope displays with your VGA card
9 May 2005, 1:57 UTC in softwareVector patches for xmame 0.94
7 May 2005, 19:32 UTCMore vector game screenshots
1 May 2005, 20:36 UTC"Dithered" output increases resolution
1 May 2005, 18:16 UTCMAME vector display on the oscilloscope
29 April 2005, 1:04 UTCWorking Z-axis
17 April 2005, 15:47 UTCVector "text" display
17 April 2005, 2:33 UTCAnimated XY display
16 April 2005, 16:53 UTCVGA to 'scope display
24 March 2005, 15:44 UTCSerendipitous optimization

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