Q1: What is HDR?
HDR refers to high dynamic range photo synthesis technology. In short, it is to combine several photos of different exposures to find the highlights and shadows of the big light than the environment. For example, in the sunset environment below, single shots must be underexposed or overexposed. Using bracketing shots, after the HDR compositing, you get detailed photos with highlights and shadows.
The image above does not use HDR, the image below uses HDR
Q2 : What are the typical errors in HDR?
HDR’s pre-shooting requires the use of bracketing technology, as the saying goes. Although HDR can help us record the details of highlights and shadows, if these details are later restored too much, it will be very distorted.
The above is a representative work of the Dutch photographer MaxRive. While using HDR technology to preserve the details of the sun, the whole photo is still rich in layers, giving a normal sunset look.
The error in applying HDR photos was mainly due to the use of automatic HDR merge parameters, and there was no re-fixing of the photos and shades of the photos. The key to the correct use of HDR technology is to modify the photo and dark tone of the photo again after the synthesis, to hide unnecessary details, to make the bright place in the photo light up, the dark place to darken, to restore the normal brightness of the photo. Compared.
- How to use HDR correctly
This article takes the following set of photos as an example to demonstrate its HDR merge process and, most importantly, the HDR merge process.
The original film of the film has a total of 3 photos, respectively, which are shot under the 2nd shot (bottom left), recording the sun highlight details, normal exposure photos (bottom right), and overexposed 2 files to record the ground shadow details. (above).
Later, we can use HDR merge with Photoshop’s own Camera Raw processor. We select “File – Open” in Photoshop, hold down the Ctrl key, click on our three originals, select them all, and click OK.
Photoshop will load these 3 original images into the Camera Raw processor. On the left side of the Camera Raw panel, we can see their thumbnails, right click the mouse, select the image and right click again, select “Merge to HDR”.
In the panel that opens, check “Align Image” and “Apply Auto Tone and Color Adjustment”. “Align Image” corrects the slight shift in the 3 shots, and “Apply Auto Tone and Color Adjustment” automatically retrieves the merged highlight shadow details.
After clicking on the merge, we can save the information of the 3 photos into a DNG format image. Since we turned on “Apply Auto Tone and Color Adjustment”, the software automatically adjusted the photo exposure, highlights, shadows, and more.
But the effect that the software automatically gives is a typical distorted HDR photo. The details are all there, but it looks very fake and weird. Next we need to fix its shadows.
Re-adjust the exposure parameters manually so that the recovery value of the highlight shadow is not too exaggerated. At the same time, the sunset was originally a dark environment, so I reduced the exposure from +1.38 to +0.75 to restore the realism.
The effect after processing seems to be much better. Next, the radial filter and the gradient filter will be applied to further repair the part of the picture.
First create a gradient filter, exposure -0.25, color temperature -2, and add a little cool color while darkening.
Then pull a few gradients in the sky to restore the dark and dark transitions of the sky.
Then set up a radial filter with a color temperature of +6 and a hue of +3, adding a layer of sunlight to the applied area. At the same time, the exposure is +0.2 for brightening. With this parameter, multiple radial filters are created near the sun, on the grass surface, and near the character, allowing the highlights of the photo to illuminate again.
Does the partially adjusted photo look more in line with our visual perception of sunset?
Further use the Nik plug-in to contrast contrast, brighten and darken the center point filter. After simple coloring, we got a brilliant sunset HDR photo.
- More HDR cases
The key to dealing with real and delicate HDR photos is the tone-repairing step after HDR merge. If you forget this step or do not handle it, you will make a more distorted photo.
The image on the left is the effect of further fixing the shading level, and the image on the right is the effect of restoring all details after HDR auto-merging.
However, some friends wondered why I had some overexposure and underexposure in the photo after I fixed the tone. In fact, let the upper part of the beam be overexposed, so that the light will be more layered and realistic.
Manual tone fix, restore photo time
The ground is properly exposed, and the messy details of the earth are hidden. After all, the overexposure and underexposure under our control are not terrible. It is important to show the readers the scene information and the atmosphere at that time, instead of pursuing more details.
HDR technology can help us record the various details in the scene. The manual tone correction can help us to hide unnecessary details and restore the layering and realism of the photos. Combine the above with us to make a review and summary:
No HDR photo: Lost details
HDR automatic merge: all details, but distortion
HDR merge + manual tone fix: Keep the details and hide unnecessary details, real and delicate.
The article is reproduced in: Reprinted from DJI Dajiang Innovation WeChat public number (ID: dji_service).
