Comments on: How a digital camera works http://jeffmatherphotography.com/dispatches/2006/11/how_a_digital_c_1/ The Post-9-to-5 Life of an International Playboy Sun, 20 May 2012 16:44:08 +0000 hourly 1 http://wordpress.org/?v=3.1.1 By: Jeff Mather http://jeffmatherphotography.com/dispatches/2006/11/how_a_digital_c_1/comment-page-1/#comment-20751 Jeff Mather Sat, 12 Dec 2009 00:30:36 +0000 http://jeffmatherphotography.com/dispatches_wp/2006/11/02/how-a-digital-camera-works/#comment-20751 Ego: You are correct, of course. I mistakenly conflated the compressed, tone-mapped pixel values with the pixel counts before they were changed by the gamma curve. Rookie mistake made at the end of the work week. :) Ego: You are correct, of course. I mistakenly conflated the compressed, tone-mapped pixel values with the pixel counts before they were changed by the gamma curve. Rookie mistake made at the end of the work week. :)

]]> By: ego http://jeffmatherphotography.com/dispatches/2006/11/how_a_digital_c_1/comment-page-1/#comment-20747 ego Fri, 11 Dec 2009 22:12:09 +0000 http://jeffmatherphotography.com/dispatches_wp/2006/11/02/how-a-digital-camera-works/#comment-20747 The author is wrong about how the sensor reacts differently to light than the eye. It has the same response as the eye, twice the amount of light is perceived in both cases as twice as bright. What confuses people is that fact that between the raw and jpeg image a non-linear tone-curve is applied, but this is to compensate for the non-linear effect that was present in old cathode-ray monitors, and which is still adjusted for in video graphical cards even though the LCD monitor is also linear. The author is wrong about how the sensor reacts differently to light than the eye. It has the same response as the eye, twice the amount of light is perceived in both cases as twice as bright. What confuses people is that fact that between the raw and jpeg image a non-linear tone-curve is applied, but this is to compensate for the non-linear effect that was present in old cathode-ray monitors, and which is still adjusted for in video graphical cards even though the LCD monitor is also linear.

]]> By: Jeff Mather http://jeffmatherphotography.com/dispatches/2006/11/how_a_digital_c_1/comment-page-1/#comment-604 Jeff Mather Thu, 03 Jan 2008 21:17:57 +0000 http://jeffmatherphotography.com/dispatches_wp/2006/11/02/how-a-digital-camera-works/#comment-604 I think the easiest thing to do might be this: 1) Bring the RAW images from your camera using whatever process you normally use, such as copying them via a card reader. You may just be able to plug your camera or card reader into a USB port and then CD to the directory containing the images. 2) Use <a href="http://cybercom.net/~dcoffin/dcraw/" rel="nofollow">dcraw</a> or a similar batch converter to transcode the raw images into JPEG. The dcraw program is free, and many people like it. 3) Call IMREAD on the converted file. I think the easiest thing to do might be this:

1) Bring the RAW images from your camera using whatever process you normally use, such as copying them via a card reader. You may just be able to plug your camera or card reader into a USB port and then CD to the directory containing the images.

2) Use dcraw or a similar batch converter to transcode the raw images into JPEG. The dcraw program is free, and many people like it.

3) Call IMREAD on the converted file.

]]> By: hari http://jeffmatherphotography.com/dispatches/2006/11/how_a_digital_c_1/comment-page-1/#comment-602 hari Thu, 03 Jan 2008 20:28:43 +0000 http://jeffmatherphotography.com/dispatches_wp/2006/11/02/how-a-digital-camera-works/#comment-602 Thank you for the reply. Excluding MATLAB, is there any other way to do it? what i mean is, i would like to collect the raw file from the camera and convert it to jpg and then read it into MATLAB using IMREAD. Thank you for the reply. Excluding MATLAB, is there any other way to do it? what i mean is, i would like to collect the raw file from the camera and convert it to jpg and then read it into MATLAB using IMREAD.

]]> By: Jeff Mather http://jeffmatherphotography.com/dispatches/2006/11/how_a_digital_c_1/comment-page-1/#comment-599 Jeff Mather Thu, 03 Jan 2008 19:40:20 +0000 http://jeffmatherphotography.com/dispatches_wp/2006/11/02/how-a-digital-camera-works/#comment-599 Hi Hari, There isn't anything in MATLAB proper to read RAW files. You might find <a href="http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=7412&objectType=file" rel="nofollow">this MATLAB Central file submission</a> useful to read them. Of course, it's about three years old, so it doesn't support all cameras. Once you get the image in, you can easily write it out using IMWRITE. Hi Hari,

There isn’t anything in MATLAB proper to read RAW files. You might find this MATLAB Central file submission useful to read them. Of course, it’s about three years old, so it doesn’t support all cameras.

Once you get the image in, you can easily write it out using IMWRITE.

]]> By: hari http://jeffmatherphotography.com/dispatches/2006/11/how_a_digital_c_1/comment-page-1/#comment-596 hari Thu, 03 Jan 2008 17:35:02 +0000 http://jeffmatherphotography.com/dispatches_wp/2006/11/02/how-a-digital-camera-works/#comment-596 how do we convert *.raw file to *.jpg/tif using Matlab? how do we convert *.raw file to *.jpg/tif using Matlab?

]]>