HP Forum Archive 17

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On / Off topic Message #1 Posted by Matthias Wehrli on 3 July 2007, 7:02 a.m. I updated my website.... - new HP-41 module list - new photo gallery: HDR pictures Matthias www.hp-collection.org

Re: On / Off topic Message #2 Posted by Maximilian Hohmann on 3 July 2007, 8:30 a.m., in response to message #1 by Matthias Wehrli Hello! Quote: ... new photo gallery: HDR pictures ... Very interesting pictures, somewhat unreal! Of course, it would be interesting to learn a bit more about the technical backgrund! What camera/sensor/scanner did you use for taking them and how do you process the images? Greetings, Max

Re: On / Off topic Message #3 Posted by Matthias Wehrli on 3 July 2007, 6:11 p.m., in response to message #2 by Maximilian Hohmann Hi I use a Nikon D80 and a very heavy tripod. I normally take 11 pictures in 10MP: -5 to +5 I currently use .jpg quality as the .raw picture is much larger but the result isnīt really better. The unsharpness is a normal result of this technic. It looks a bit misterious. Very interesting is the picture with the moving leaves. Matthias

Re: On / Off topic Message #4 Posted by Maximilian Hohmann on 4 July 2007, 2:40 a.m., in response to message #3 by Matthias Wehrli Hello! Quote: Very interesting is the picture with the moving leaves. Yes, definitely! Really looks like it was taken on a different world... Just to play around a little bit, last night I re-processed a single raw-file of my camera (Sigma SD10 with Foveon sensor, which has a very good dynamic range) into a (pseudo-)HDR image and was impressed how much hidden detail this technique was able to reveal (for the price of incrased noise in this case): http://www.bombie.de/tmp/IMG08930_HDR.jpg BTW, have you come across Helicon Focus yet ( http://www.heliconsoft.com/heliconfocus.html )? It is a somewhat related technique, that combines images from the same scene taken at different focal planes into one super-sharp "impossible" picture that is in focus everywhere (ideally at least). When you dont have enough planes or if you get moving objects in your scene, the effect is somewhat similar to your ghostly leaves: http://www.bombie.de/tmp/rapsfeld.jpg It is really fascinating to witness, how increasing processing power changes (amateur) photography, I only wish I had a little more time... Greetings, Max

Re: On / Off topic Message #5 Posted by Matthias Wehrli on 4 July 2007, 4:35 a.m., in response to message #4 by Maximilian Hohmann Hi Your pictures shows a airplane. In true HDR this is not possible as HDR doesnīt allow to take pictures of moving elements. How did you converted this picture into HDR? Matthias

Re: On / Off topic Message #6 Posted by Maximilian Hohmann on 4 July 2007, 4:54 a.m., in response to message #5 by Matthias Wehrli Hi! Quote: How did you converted this picture into HDR? I processed one singe raw-file with different contrast and brightness settings into four diffrent images: One optimised for the moon, one for the aeroplane, one for the smoke and one for the diffuse clouds in the background, then I combined these four images into this HDR (or pseudo-HDR, whatever you want to call it) image. The imaging sensor of my camera ( http://www.foveon.com ) is said to have twice the dynamic range (but less pixels) than the more common "Bayer"-sensors, so it is possible to extract all this information from a single raw file. Greetings, Max

Re: On / Off topic Message #7 Posted by Meindert Kuipers on 4 July 2007, 5:13 a.m., in response to message #6 by Maximilian Hohmann I do have some more experience with this, although I cannot disclose any details. I have worked with Bayer sensors with 12-bit dynamic range (per pixel!) which have the possibility of tweaking the amplifier settings. By taking the raw Bayer images and applying other filters much more information can be extracted. Especially since the green has double the resolution and has most of the luminosity information nice tricks can be done with this. But this is getting way OT ... Meindert

Re: On / Off topic Message #8 Posted by Maximilian Hohmann on 4 July 2007, 5:30 a.m., in response to message #7 by Meindert Kuipers Hello! Quote: I do have some more experience with this, although I cannot disclose any details. Well, my experience with this is limited to something like 15 minutes... But what a pity that you can't tell us more! Quite a few years back I did my ph.d. on radar/microwave imaging and in the end you can sum it all up with "extract as much as you can from the raw data". Hopefully, future raw-data converters that come with digital cameras will include some kind of HDR-function! Quote: But this is getting way OT ... Well, if we write a little program that does the necessary calcultions for HDR image generation on an hp67, then we are back on topic, aren't we :-) Greetings, Max

Re: On / Off topic Message #9 Posted by Dave Shaffer (Arizona) on 4 July 2007, 2:00 p.m., in response to message #8 by Maximilian Hohmann re: "Quite a few years back I did my ph.d. on radar/microwave imaging" Staying off topic (!), what exactly did you image? Was it single dish or synthetic aperture? I do radio astronomy interferometry, and we, too, are always trying to get that last little bit of information out of the data (usually by worrying about Fourier components).

Re: On / Off topic Message #10 Posted by Maximilian Hohmann on 4 July 2007, 4:28 p.m., in response to message #9 by Dave Shaffer (Arizona) Hello! Quote: what exactly did you image? Was it single dish or synthetic aperture? I do radio astronomy interferometry, and we, too, are always trying to get that last little bit of information out of the data (usually by worrying about Fourier components). We did high-resolution multi-frequency synthetic aperture (and "inverse synthetic aperture" which corresponds more or less to computer tomography, but with microwaves instead of x-rays) imaging of natural targets like plants and soil samples. One aim was to obtain a radar signature database for classifying satellite based radar images of the Earth. The european satellite ERS-1 was launched while I did my work, so we actually could test some of our methods on its early raw data sets. The other aim was to develop and test concepts for three dimensional imaging through interferometry and 3-D-inverse synthetic aperture radar at laboratory scale ( http://www-emsl.jrc.it/ ) So there are some parallels to your work, especially the Fourier components :-) And we used mainly equipment of hp in our lab - to come back to the topic - but no pocket calculators I'm afraid! Greetings, Max Edited: 4 July 2007, 4:29 p.m.

Re: On / Off topic Message #11 Posted by megarat on 4 July 2007, 7:37 p.m., in response to message #3 by Matthias Wehrli How do you merge the exposures into the final image? Do you use the "Merge into HDR" feature of Photoshop CS2? (I only have a copy of CS, so I'm interested in any other techniques you might be aware of.)

Re: On / Off topic Message #12 Posted by Paul Brogger on 5 July 2007, 12:19 p.m., in response to message #3 by Matthias Wehrli That explains the ghostly figures walking on the platform . . . Really, a stunning effect. Thanks again! Edited: 5 July 2007, 12:28 p.m.

Re: On / Off topic Message #13 Posted by Paul Brogger on 3 July 2007, 12:27 p.m., in response to message #1 by Matthias Wehrli Gorgeous. One of the train station pics is my new desktop background. Thank you!

Re: On / Off topic Message #14 Posted by Thomas Radtke on 3 July 2007, 2:41 p.m., in response to message #1 by Matthias Wehrli Have your HDR pictures undergone something like unsharp masking? They look a bit equalized for brightness. Extremely tasteful and interesting to look at, though.

Re: On / Off topic Message #15 Posted by Chuck on 3 July 2007, 4:22 p.m., in response to message #14 by Thomas Radtke "They look a bit equalized for brightness." ============================================ That's what HDR does. You take 3 or more photos at different exposures and combine them. The HDR process combines the best parts of all (shadows, midtones, highlights, etc) to make a picture that usually a sinlge photo can't capture, but often it appears to be more like our eyes see it (because our pupils change).

Re: On / Off topic Message #16 Posted by Thomas Radtke on 3 July 2007, 5:25 p.m., in response to message #15 by Chuck Ah, I thought there were already CCD chips capable for this range and that such a beast has been used :^).

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