More video options

The video functions of small cameras are often overlooked by photographers. We take photographs, not video clips, right? Well, with the CHDK activated you may change your mind. Video sequences are quite memory-hungry. That is the reason why the camera compresses all video frames. Doing so saves a large amount of memory but also reduces [...]

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Edge overlay

The CHDK Edge Overlay function is able to extract the edges from an image as soon as you half-press the shutter button and overlay the resulting diagram with the current content of the display. This allows viewing the previous shot and the current shot in context, making it easy to register images and apply techniques [...]

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Focus stacking, Depth of Field

Depth of Field (DOF) is often a problem in photography. Only a distance range within the image is sharp, while objects outside that area are blurred. In particular, telephoto shots, macro work, and tabletop photography are hampered by this problem. The traditional remedy is to stop down (or, in the case of view camera and [...]

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HDR and tone mapping

High Dynamic Range (HDR) and Dynamic Range Increase (DRI) Photography have become quite popular among digital photographers. Both techniques are used for recording contrast ranges that are beyond the maximum contrast range of a state-of-art camera sensor [Howard2008][Bloch2007]. Photographic scenes — especially those in full sunlight—can have a dynamic range of 16 to 25 Light [...]

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General bracketing notes

Setting up the camera for an unlimited series of bracketing shots is very easy under the CHDK. Just go to the Bracketing submenu and set the values for the entries found there: To enable bracketing, you must also set Disable Overrides in the submenu Extra Photo Operations to Off (section 4.3.1) if you enabled the [...]

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Bracketing

Bracketing is a camera function that produces a series of photos with varying settings. Traditionally, bracketing was used to obtain an image with perfect exposure. First, an image with the measured exposure was made, then an image half an f-stop overexposed, then an image half an f-stop underexposed, then the same with a full f-stop. [...]

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More RAW processing

The possibilities don’t stop with the RAW processing discussed in section 4.5.5. The context menu of the file browser (see section 4.10.1) opens a whole new world of addititional RAW processing options. You can reach the file browser through alt >menu >Miscellaneous Stuff> File Browser or alt > menu > RAW Parameters > RAW Develop. [...]

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In-camera RAW processing

You don’t necessarily need a PC to process RAW files. With the CHDK it is possible to develop RAW files within the camera. The selected RAW file will be converted into a JPEG file. Why should you do this? The advantage is that you can apply some processing parameters after a shot has been taken, [...]

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Processing RAW images

Many photo editors such as Photoshop, Paint Shop Pro, Picture Window, and so on can import RAW images. And then there are the specialized, work-flow-oriented RAW developers such as Aperture, Lightroom, CaptureOne, Helicon Filter, BreezeBrowser, SilkyPix, DxO, RawTherapee, and others. These programs have highly specialized tools for developing RAW images. Many lens and sensor imperfections—such [...]

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Other RAW parameters

RAW files saved by the CHDK are not equipped with EXIF data (DNG files are). This sounds like a drawback because EXIF data are very useful for processing and archiving images. Vital information such as exposure time, aperture, ISO speed, focal length, distance, etc., would be missing without the EXIF data. But because the CHDK [...]

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DNG photos directly from your camera

The RAW format produced by the CHDK has some restrictions. First, CHDK’s RAW images are not equipped with EXIF data. Second, the RAW format produced by the CHDK is not understood by all RAW converters. Some simply refuse to open the image. A good choice is the program RawTherapee, which is available for the main [...]

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Bad Pixel Removal

Bad Pixel Removal works quite differently and only in connection with DNG. A bad pixel map is created in advance. In section 4.5.2, we already discussed how such a map is created. When running, the script badpixel.lua grabs a bad pixel map from the camera (normally used for the creation of JPEG images) and stores [...]

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Dark Frame Subtraction

Dark Frame Subtraction is a common technique for removing unwanted artifacts from an image. When an image is taken, the camera will make two exposures: one with an open lens, the other with a darkened lens. The second exposure will only show noise and hot pixels. Subtracting the second image from the first will remove [...]

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Basics of shooting RAW

RAW images are nothing more than the unmodified sensor data produced by the camera. JPEG images, in contrast, are the result of a development process: the color temperature is estimated and applied, the image is sharpened, noise is removed, and the contrast is compressed. Scenes with stark contrast usually have some highlights clipped. So, the [...]

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Focus

The focal system of Canon compact cameras is dominantly based on an autofocus system. Only some cameras in the higher price range allow manual focusing. The autofocus system is augmented by special focus modes such as Macro or Infinity, which can be set manually. Over the years, the focus system has become more and more [...]

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Using curves in the CHDK

Custom Curves are another option in the CHDK to control the outcome of a shot. Curves are applied after an image has been taken; they don’t influence exposure settings such as aperture or sensor speed. They simply modify the digital data delivered by the sensor before it’s packed into a JPEG file. This can make [...]

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Flash functionality in CHDK mode

Most Canon compact cameras have rather limited flash functionality. My SD1100, for example, supports the following modes: Automatic, Off, and On (in manual mode). Red-eye correction and a red-eye lamp can be switched on, and in manual mode there is a Slow Sync option. However, there is no way to control the flash power. This [...]

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Night photography

In the past, night photography has not been easy with digital cameras. At high ISO values, the noise in the image goes up. Shooting at low ISO values is not always possible — lack of a tripod may be just one reason. And at long exposure times, the camera’s sensor tends to produce artifacts: hot [...]

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High-speed photography

One amazing feature of the CHDK is the provision for ultra-short shutter speeds. Before we go into the details, let’s take a look at general shutter technology. Traditional cameras from the analog era use mainly two types of shutters. One is the focal plane shutter, which is also used in DSLRs. Here, two curtains move [...]

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Zebra feature identifies image areas that are under- or overexposed

Another convenient way to control exposure is the Zebra feature. While the histogram informs you about the tonal range of the complete image, the Zebra feature identifies image areas that are under- or overexposed. These areas are displayed with a pattern overlaid on the image to make them stand out visually. When enabled in the [...]

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