Reviews, VFX

Hydra 4, the HDR app, brings Metal support, zonal tone mapping

hydra 4 interface

Hydra, the HDR app by Creaceed, has been upgraded to version 4. It has been optimised for Metal, has a new easy-to-use translucent user interface, and comes with an excellent automatic image alignment system. It offers less brilliant manual image alignment, and removal of ghosting artefacts, both with a region delineation tool. In addition, Hydra 4 works with a highly accurate 128-bit internal format.

When I launched Hydra 4, the first thing that caught my attention was its user-friendly interface. You start out with a large view on the image the app itself thinks to be the reference image. Each image in the group of images that will make the HDR version has a couple of controls, including exposure and sharpening. The sidebar with the image thumbnails and controls has options to manually set the alignment and ghosting.

hydra 4 interface

You align images with the help of outlines that make the superimposed images look like a bad cartoon. By dragging multiple edges until they match perfectly you can create an aligned / ghost-free HDR image. Although you can create as many of these alignment areas as you want, I found it very difficult to align the five images in my test group perfectly. Hydra 4 aligned these images with no problem in automatic mode, though.

Once you’re happy with the alignment and ghosting, the app calculates the HDR image. Hydra 4 is a speed demon with a significantly faster result than other HDR apps or its predecessor.

Customising your HDR image

hydra 4 hdr controlsThe sidebar has two tabs: Presets and Customisation. The Presets tab has 12 presets to choose from. Personally, I am not a great fan of these presets, but many people like to start from a look created by someone else. For them, the 12 presets are probably on the skinny side.

Better news comes in the customisation tab. Hydra 4 has a much improved tone mapping algorithm. First of all, the colours of the default HDR image (the one that appears after Hydra 4 has developed your HDR image) stay very close to those of the original images. That’s a good thing for people who want to create a natural look. It’s also good for those who like the typical HDR look with forced saturation and sharpness as it’s very easy to create these when you start from an accurate colour original.

Another positive is that double-clicking on a value returns the control to its initial state. You can experiment as much as you like. It’s easy to undo and start over. Two controls are usually only found in non-HDR apps: Shadow boost and Highlight Recovery. The two combined allow you to further open up the far ends of the image’s dynamic range.

Zonal tone mapping

For creative purposes there’s also a Hue control to give your end-result a warmer, colder or otherworldly look. But wait, there’s more. There’s an option called “Scope”. When you click on the drop-down menu next to this option, you’ll see a whole world of tine mapping options open up in front of your eyes. The menu gives you access to individual tone mapping adjustments for bright, dark, red, green and blue tones. Selecting anything different from the default “Overall” option makes an eye icon appear. Clicking on that icon reveals a mask that shows you which areas in your image will be affected by your pinpoint adjustments.

Hydra 4 lets you take up to four snapshots, so you can compare your results against previous adjustments. In addition, a “curtain” control allows you to compare between the original image and the adjusted one. I fully realise this sentence is confusing, as there is more to it when you’re developing a HDR image. In Hydra 4, this capability gives you the option to compare your latest adjustment with the raw composited image or with one of the composing photos. There’s also a slider that lets you adjust viewing exposure for the raw composite image.

This comparison view is obviously truly powerful and gives you plenty of insight in how you have improved (or worsened) the original.

Mundane HDR capabilities

Hydra 4 supports importing single or multiple JPG, RAW, HDR or EXR images. It renders out to JPG, TIFF, HDR and EXR, in colour spaces that include sRGB, ProPhoto, AdobeRGB and more. What I couldn’t see for myself, but which Creaceed lists as a feature is the unique support for deep and wide colour displays such as the 30-bit DCI-P3 display of the latest iMac 27in.

Finally, Hydra 4 integrates seamlessly with Apple Photos.


While Hydra 4 isn’t as powerful or feature complete as Aurora HDR, it’s certainly able enough to make HDR images quickly with enough control over the end-result to create something truly unique and tasteful.

Aurora HDR is for the HDR enthusiast who wants to create the ultimate HDR image or tap into Tray Ratcliffe’s presets. Hydra 4 is for the rest of us. It costs approx. €55 ($59.99).

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J.D. – Copywriter – Tech. Writer – Editor at Visuals Producer – Contributor at Photoshop User, Studio Daily – Sub-editor at RedShark News