![]() If Photoshop can't align them, you may have to use another program like Deep SkyStacker to align them first. Set the White Break PointĪll four images then open, and PS tries to align them if the "Attempt to Automatically Align Source Images" box is checked. Photoshop analyzed the images, and re-assigned EVs of +3, +1, 0 and -2 to the images. I doubted this was the case and suspected that it may have been the negative numbers that were a problem, so I used EVs of 1, 3, 4 and 6 respectively, and it was able to construct an HDR image with these numbers. ![]() However, when these numbers were input into the dialog box and assigned to the correct exposures, an error message came back that said "not enough dynamic range to construct a useful HDR image". Four minutes at f/8 is equal to EV -2, and so on. ![]() So, one minute at f/8 at ISO 100 is equal to EV 0. Each EV step is equal to one stop, a halving or doubling of exposure. If the images are already open in Photoshop, select Open Files under the Use: drop-down menu.įor digital files, exposure data in the EXIF files are used, but for film images, the EV of each individual image must be specified. The HDR Command is accessed under the File > Automate > Merge to HDR. Images were shot with an Astro-Physics 130 EDT f/8 refractor.Īs is typical of exposures of the Orion nebula, the core of the nebula is completely burned out in the longer exposures.Īs previously described, there are several methods of combining these different exposures using layer masks in either 8 or 16 bits, but Photoshop HDR function actually creates data that can span a tremendous dynamic range in 32 bits of tonal depth per color channel. The originals and the exposure times can be seen below. The images can be 8-bit jpeg film originals, or even 16 bit raw digital camera image files.īelow is a very quick and dirty example done with four film images of the Orion Nebula, each made with a different exposure. This feature is interesting for astrophotographers for those objects, such as M42, which have too large of a dynamic range to be captured in a single image. It offers the ability to combine multiple individual images with different exposures into a single 32-bit floating-point image with expanded dynamic range. Photoshop offers a function for creating 32-bit High Dynamic Range (HDR) images.
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