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About easyHDR
EasyHDR is an image processing software that produces and tonemapps High Dynamic Range images from photo sequences taken with a normal digital camera. EasyHDR can also tone map already created HDR images saved in Radiance RGBE (*.hdr) format or 48-bit and even 96-bit TIFF. You can also process RAW images from your camera by loading them directly into the program. Another great feature is single Low Dynamic Range (LDR) photo enhancement.
What is a HDR image?
High Dynamic Range image covers much wider dynamic range (light to dark ratio) than a normal digital camera can record (due to noise and overexposure). A HDR image is created by blending an image sequence of photos taken at different exposure values (various exposure times or ISO sensitivity). Each photo in the sequence shall cover a part of the dynamic range of the photographed scene. The resulting HDRi will therefore contain the full information from all of the photos.
How to take an image sequence?
If you try to photograph a scene and get some unwanted over- or underexposured areas you may consider taking a bracketed sequence that could be later blended to HDR and processed. The easiest way to do so is to turn on autobracketing (AEB) in your digital camera, set the number of photos in the sequence and the EV (Exposure Value) spacing. The 0EV photo will be taken at the exposure time, ISO and the f-number measured by the camera as the best for the particular scene. The other photos will be deliberately underexposed (negative EV) or overexposed (positive EV) so they will contain details that are lost in the 0EV photo due to noise and overexposure. The photographed scene should be static - there should be no movement or light change during the photo sequence acquisition, otherwise ghosting effect will be visible in the assembled HDRi. Therefore you should use a tripod to take the photo sequence. EasyHDR, however, has a built-in auto-alignment feature that compensates for shift and rotation between photos, so taking a photo free-hand won't necessarily mean a bad result. If the autobracketing isn't sufficient you may want to manually vary the exposure time, with the constant ISO and f-number. When you i.e. take 3 photos at 1/200 (A), 1/100 (B) and 1/25 sec (C), this will mean that the photo (A) is underexposed by 1 EV relatively to the photo (B) and the photo (C) is overexposed relatively to (B) by 2EV - so you have a photo sequence: -1EV, 0EV and +2EV.
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Photo sequence and the tonemapped HDRi
What is tone mapping?
The pixel value to real scene radiance ratio is linear in case of the assembled HDR images. The CCD and CMOS sensors both have linear sensitivity too, but the photo taken with a digital camera undergoes processing before it is stored as JPEG on the memory card. That processing include contrast (or dynamic range) compression, so the photo looks natural when is displayed on a computer screen. We could do the same with the HDR images (tone mapping with a global operator), but this will prevent us from preserving the proper local contrasts in the output photos. That's why special, local operators, are used to tonemap HDR images. Tone mapping simply allows the HDR images to be displayed on a screen or printed.
What are the benefits of LDR enhancement with easyHDR?
In many cases the photographed scenes do not characterize with very wide dynamic range, so taking an image sequence in order to assemeble and tonemap a HDR may be too much effort. Also, by taking a RAW photo, instead of JPEG you can achieve a slightly higher dynamic range, so a single photo may be sufficient (example). Below you can see a single JPEG photo taken with Canon 350D and the result enhanced with easyHDR:
Here are some key features of easyHDR Pro
· Image file format support
· loads: 24/48/96-bit TIFF (uncompressed or deflate compressed), Radiance RGBE (.hdr), 24-bit JPEG, 24-bit BMP and FITS
· saves: 24/48-bit TIFF (with or without compression), 24-bit JPEG (without loosing EXIF data), Radiance RGBE (.hdr) and 24-bit BMP
· built-in converter DCRAW can convert RAW images from most digital cameras (among them: .RAW; .RW2; .CRW; .CR2; .RAF; .MRW; .NEF; .ORF; .DNG; .PEF; .X3F; .DCR; .KDC and .SRF) to extended dynamic range, 48-bit TIFFs (without quality loss).
· Manual alignment: uses a planar stretching method to compensate for shift, scale, rotation and perspective misalignment.
· Auto alignment: easyHDR is able to automatically compensate for shift and rotational misalignment.
· Features 3 HDR generation methods: True HDR, Smart Merge and simple Image Stacking.
· HDR generation with an anti-blooming option.
· Global and local tone mapping operators with Local Contrast function.
· Curve adjust tool.
· Histogram black & white point clipping. Manual or automatic.
· Preview: process only a selected area or the whole, resized photo.
· Program settings can be saved to a file and later loaded. You can also save and load entire projects.
· Batch processing - you can prepare a list of image sequences (with associated settings) or previously saved projects, choose result file format and destination directory, click "Do all" button and leave easyHDR to do the whole job automatically. You can also do LDR enhancement or HDR file generation only (without tone mapping).
· Postprocessing, while still working on floating point data (no quantization losses). Available are: gaussian blur, unsharp mask, median and bilateral (noise removal) filters and also two color adjustment tools: neutral point (white balance) and sample/target balance. |
