Cyborg time

About two years ago I started with a friend - who happen to be a color scientist as well - a series of research experiment having for goal to study projector displays and wondering if we could evaluate some of theirs properties - such as response curve and color gamut - without proper measuring device - meaning without expensive measuring devices.

Said like that I admit it doesn't sound very sexy. But that were the fun come in, it is not because it doesn't sound über cool that the approach can't be fun. Inspired by the work of other researchers where instead of using measuring devices experiments were conducted using a panel of human observers. A series of images were presented to the observers. Based on their decision, to say if pairs of color patches were identical in brightness/intensity - one made of a single gray continuous value and the second made using halftone technique - the famous response curve could be described. There is so much things you can do with the response curve but I will not pursue in that direction today.

Our idea is simple and we are not the first to have had this idea: to replace the observer by a camera, a webcam. Three simple reasons to do so: for having been several time one of the observer I know it is super annoying to be part of such experiment, mimicking an eye with a camera is a nice challenge and webcam are cheap. And not to mention that opencv is there to avoid you to loose to much time in accessing the video stream of your webcam and programming in Python is pleasant.

To be short, we are re-doing a pair single color patch comparison. One patch is a continous patch and the second halftoned.  The project is called devForWebCam, it's programmed in Python and located here. The code should help to setup an experiment in order to gather data.

Pano for the people 2

I "closed" this project by adding some final examples. More precisely examples where something can go wrong and showing what it means in images.

One important thing to be able to create a beautiful little planet is to have made first a full spherical panorama picture. This panorama has to be presented as a rectangular image, an equirectangular image of ration 2:1, this means the virtual camera that would have taken this image has an equirectangular lens of field of view 360°. That is the requirement for my scripts and function that generate template file to control hugin. But you are free to distort any rectangle images with different ratios.

All the codes and guidelines here panoToLittlePlanet.

What does it mean to generate a little planet from the south hemisphere of full spherical panorama? The answer below:

full spherical image with only the south hemisphere visible.

the resulting little planet.

Pano for the people

The past fews day, actually during Chistmas vacation, I started to think how can I make easier the process of creating little planet panorama pictures. Before my android phone decided to update its software I could directly from the phone generate the little planet from a full spherical panorama, not anymore. That's not a bit problem because using hugin you can in three to four click generate a little planet. This means to perform some remapping from an equirectangular panorama.

To avoid having to open hugin again and knowing that you can script hugin I created python script with some functions to automatize this process.

The code and explanation are beautifully stored and located on my public github account panoToLittlePlanet.

The famous little planet pictures are in this flicker little planet photo album.