![]() Sometimes the rows of green pixels create a mesh effect with VNG, or a maze effect with AHD, or other undesirable artifacts. Using more green pixels results in an image with less noise and finer details. (Some Sigma and Sony cameras, to give two examples, do not use Bayer array sensors.) These have twice as many green pixels as yellow or blue pixels, because our eyes are more sensitive to green. ![]() Most camera sensors use what is called a Bayer array. Interpolate RGB as Four Colors is occasionally useful. However, it is not that cut-and-dried, and the best way to figure out which one gives the best results for you is to try all of them. The short story is Bilinear is the fastest and lowest-quality, and AHD is the slowest and highest-quality. What do these mean? That is a long story. On the Quality drop-down menu there are four choices: Bilinear, VNG, PPG, and AHD. If this is not checked it imports at 8 bits, and then you might as well just use JPGs. Camera sensors are made up of pixels in the three primary colors red, green, and blue (RGB). Demosaicing is the process of translating data from the camera’s sensor into detailed photos with many colors. Now let’s go to the RAW Decoding section and learn what all these strange-sounding settings mean.įirst make sure that Demosaicing - 16-bit color depth is checked. I fiddle with the settings a lot and can’t settle on a decent default set, so I leave the box checked to give me more tweakability. Un-check the “Use Raw Import Tool to handle Raw images” box to make the image editor import RAW images automatically with your default settings. Configure this in Settings > Configure Digikam > Image Editor. You can have RAW images imported automatically when you open a photo in the editing window, or do it manually. There is no universally right choice and you must use what pleases you. Casual snapshots, or photos taken under perfectly-controlled conditions don’t need to be in RAW. File sizes are large, and on many cameras shooting RAW is slower. Working in RAW gives you much greater dynamic range for editing, and more scope to rescue photos with exposure, noise, sharpness, or white balance problems. (CHDK-supported cameras are usually 10 bits.) This is converted to a 16-bit file by your RAW converter, and then you have 65,536 brightness levels. Most camera RAW files are saved at 12- or 14-bit depth your cameral manual should tell you. Most RAW files are based on the TIFF file format. The big “secrets” are headers and image metadata such as date, exposure, and ISO settings. There isn’t a single RAW file format, because all the camera vendors like to use their own special secret RAW formats. RAW files are minimally-processed sensor data. A higher compression ratio results in smaller file sizes, and that smaller size comes at a cost of throwing away information. Then it applies whatever compression level you have set. The camera, which is really a little computer, manipulates the sensor data to create the photo: white balance, contrast, brightness, and color hue and saturation. At 8 bits you have 256 brightness levels. When some brainiac figures out cool hacks, as with CHDK, the Canon Hack Development Kit for Canon point-and-shoot cameras, all kinds of advanced features are unlocked. This is an artificial distinction as lower-priced cameras can shoot RAW just like their more expensive siblings. Higher-priced cameras support JPG, RAW, and sometimes TIFF. Lower-end digital cameras support only JPG. Even if Digikam 2.0 makes drastic changes to the interface the principles and editing tasks are the same, so hitch up your pics and follow along! I tried Fedora 14, which has Digikam 1.9, and had various misadventures, so after all that futzing with distros I went back to good old Debian Sid and Digikam 1.2. ![]() Don’t use this if you need a stable, reliable system. If you want the latest beta release without compiling from sources, you can use Phillip Johnsson’s PPA (Personal Package Archive) repository for Maverick. Debian Sid and Ubuntu 10.04 (Lucid) have version 1.2, and Ubuntu 10.10 (Maverick) ships with 1.4. The 1.x series is no longer supported as the Digikam team are working towards a stable 2.0 release, scheduled for June 2011. Want to claim the power for your own photo efforts? Read on and I’ll show you how to tame RAW photos on Linux with Digikam.Ĭhoosing which version to use was the hardest part of writing this article - the excellent Digikam development team, led by Gilles Caulier, have been shoving releases out the door at an astonishing rate, and 2.0 beta4 was just released. Linux lovers have the perfect tool for harnessing the RAW power in Digikam, via the built-in LibRaw. Shutterbugs have found big power in understanding and manipulating digital photos in RAW formats.
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