EasyHDR is an image-processing and HDR photography software application for Windows and macOS (HDR stands for High Dynamic Range). It generates and tone-maps High Dynamic Range images from photo sequences taken with digital cameras. It can import many image formats, including JPEG, 8/16-bit JPEG2000, HEIF/HEIC, AVIF, 8/16-bit TIFF, PNG, FITS, and almost any RAW photo format thanks to integration with LibRAW. EasyHDR supports RAW files from Canon, Nikon, Sony, Fujifilm, Panasonic, Pentax, Olympus, Leica, Kodak, Samsung, GoPro, DJI, and others, including RAW images taken with smartphones. Additionally, easyHDR can import OpenEXR (*.exr), Radiance RGBE (*.hdr), and 32-bit floating-point TIFF HDR images generated by other HDR photo-processing software.
In order to produce a well-exposed and dramatic-looking photo, it is not always necessary to use a series of differently exposed images. Sometimes a single photo is enough, especially when it is a RAW file. That's why easyHDR includes the option to process just one image - a feature called LDR (Low Dynamic Range) enhancement.
High Dynamic Range images cover a much wider dynamic range (the ratio between light and dark areas) than a normal digital camera can record because of noise and overexposure limits. An HDR photo is created by blending a sequence of images taken at different exposure values (using various shutter speeds, ISO sensitivities, or aperture settings). Each photo in the sequence captures a different part of the scene's dynamic range. When combined, the resulting HDR image contains the full range of detail from all the photos.
If you photograph a scene and notice unwanted overexposed or underexposed areas, you may want to take a bracketed sequence that can later be blended into an HDR image and processed. The easiest way to do this is to enable Auto Exposure Bracketing (AEB) on your digital camera, set the number of photos in the sequence, and choose the EV (Exposure Value) spacing. The 0 EV photo will be taken using the exposure time, ISO, and aperture that the camera considers optimal for the scene. The other photos in the sequence will be deliberately underexposed (negative EV) or overexposed (positive EV) so that they capture details lost in the 0 EV photo due to noise or clipped highlights.
The scene should be static, there should be no movement or changes in lighting during the sequence, otherwise a ghosting effect may appear in the final HDR image. Most ghosting can be corrected using easyHDR's manual or automatic ghost-removal tools. Using a tripod is recommended, but handheld shots can still be used; easyHDR includes both manual and automatic alignment methods capable of compensating for shift, rotation, and perspective misalignment.
If your camera's auto-bracketing options are too limited, you can manually adjust the exposure time while keeping ISO and aperture constant. For example, if you take three photos at 1/200 s (A), 1/100 s (B), and 1/25 s (C), photo A is 1 EV underexposed relative to B, and photo C is 2 EV overexposed relative to B. This gives you a sequence of -1 EV, 0 EV, and +2 EV. You can find more information about Exposure Value, along with an Exposure Value calculator.
In an assembled HDR image, the ratio of pixel values to the real scene's radiance is linear. CCD and CMOS sensors also respond linearly, but photos captured by a digital camera are processed before being saved as JPEGs on the memory card. This processing includes contrast (also called dynamic-range) compression, which ensures the image looks natural when displayed on a screen.
The same type of global compression could be applied to HDR images, but doing so would reduce local contrast and make important details less visible. For this reason, specialized local tone mapping operators are used. Tone mapping is the procedure that converts high dynamic range data into a form suitable for display on Standard Dynamic Range (SDR) screens or for printing, while preserving as much detail and local contrast as possible.
In many situations, the photographed scene does not have an especially wide dynamic range, so taking a full image sequence to assemble and tone-map an HDR image may be unnecessary. When shooting in RAW rather than JPEG, you also capture a slightly wider dynamic range, which means a single photo may be enough (RAW enhancement example). Below you can see a single JPEG photo taken with a Canon 350D, along with the result after applying HDR processing in easyHDR.
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