Noise-free HDR: Expand Dynamic Range and Get Rid of the Noise

Theresa Stone

Dynamic range expansion by blending several images taken at different exposures is well known, adopted by photographers and implemented in a number of software tools. However, while the exposure blending works well for creating HDR images, further tone mapping often produces the images with a lot of noise, especially in dark areas of the scene. The amplification of underexposed pixels fills the shadow areas with noise, which lead to the loss of details and textures.
New advanced weighting technique, implemented in PhotoAcute Studio application, solves this problem. The algorithm weights each pixel in each image determining how properly is it exposed, and never places underexposed pixels into the output image when better exposed pixels are available from other images. Properly exposed pixels are then blended to reduce the noise even more. Additional processing is applied then to analyze the picture and prevent any artifacts.
As a result, the noise is almost completely removed from the image with no loss of details. Fine details and textures, formerly lost in the noise, become visible.
The same functionality can be used in usual photography to eliminate the noise even from the deep shadows of the images, by blending normally exposed and overexposed photos of the same object.
PhotoAcute Studio performs precise image registration, so it can be used for the images taken without a tripod.
This technique will be interested and useful for all photographers, who take high dynamic range images. Undoubtedly, it is indispensable for professionals, for whom high quality of the images is essential.
Detailed description of Noise-free HDR method is available at: https://photoacute.com/noise-free-hdr.html
Besides the expansion of dynamic range, PhotoAcute Studio increases spatial resolution, extends the depth of field and corrects chromatic aberrations. It supports variety of image formats, including RAW, DNG and TIFF. The application can save the results in DNG format, providing RAW-in-RAW-out processing and can be added to any image processing workflow.
PhotoAcute Studio runs under Windows, Mac OS X and Linux. Its user interface is quite simple and allows performing image processing in a couple of clicks.
Detailed description of PhotoAcute Studio features, online help and examples gallery are available at https://photoacute.com
PhotoAcute Studio can be downloaded from: https://photoacute.com/studio/download.html