![]() Quickly, HDR stands for High Dynamic Range. I say “actual” because there has been a lot of noise (confusion) about HDR over the past few years where it has been relegated to a look or an effect used in Photography to give a grungy or otherwise overprocessed look. I’m super excited and I have a ton of content and tutorials I have created on actual HDR. Keep an eye on this space, because HDR is the future and it’s coming at you fast. ![]() There is color and details in areas that used to only appear white on SDR (Standard Dynamic Range) screens. (I’ve been talking about this distinction for YEARS). Just for clarity, I’m talking about true HDR, not the HDR effect. (skip to Enabling the new features section if you want to skip my HDR explanation and HDR vs fake HDR rant) At this time, Chrome browser supports the HDR image format jpg XL (jxl). These new features enable you to output a true HDR image for viewing on HDR enabled screens like monitors, iPads, phones and laptops including Apple XDR screens. But this data must eventually be converted to 8 bits for output to a monitor or printer.New HDR Features in Camera Raw in PhotoshopĪdobe has added some unreleased new features in Photoshop. The resulting 32-bit High Dynamic Range image contains data that spans a tremendous dynamic range compared to a single exposure. No image adjustments or manipulations were done to the image after conversion to 16 bits, except a final conversion to 8 bits for saving as a jpeg file. The resulting HDR image can be seen at left. This image was then be converted to 8 bits for saving as a jpeg file for display below. These parameters will have to be explored in more depth. I moved the black point slider to the right and adjusted the brighter mid-tones in the image as seen in the screen shot at right.Īdjusting the Radius and Threshold almost seemed to give an true, non-sharpening unsharp mask effect. I chose the Local Adaptation method, which gives access to the Toning Curve and Histogram. Here, under Method, the HDR conversion dialog box opens offering a choice of four different methods of converting the 32-bit image to 16 bits. It is during this step in the process that the data is manipulated and made to look like a normal photographic image. This 32-bit image is then converted to 16 bits using the Image > Mode > 16 bits/channel command. The image is then saved as a 32-bit per channel Portable Bit Map (PBM) format file. For this example, I moved the slider all the way to the right. Once Photoshop analyzes the images and combines them, you adjust the "Set White Break Point" slider. 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.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |