HDR

Digital Noise & HDR Photography - Via Macphun

Here's another from my series of Educational blogs with Macphun!  Be sure to check them all out on https://aurorahdr.com/blog


Noise is nearly unavoidable in digital photography unless you’ve got the absolute perfect lighting conditions and you can use the absolute lowest ISO setting on your camera possible! This is due to the sensor design of digital cameras, and in bad light or high ISO situations, will leave you with grainy or strangely colored dots and patches throughout your whole photograph. Simply put, the higher your ISO, the stronger the presence of noise in your image.

Here are two BEFORE photos:

So how does this apply to HDR images? The very nature of Tone Mapping and HDR tends to amplify existing noise in your image. So if you’ve got a few high ISO brackets, the resulting HDR image is going to be exponentially noisier than your starting points. Using 3 brackets that are 400 ISO each on their own, we'll get pretty clean images. 

However, when merged, the darker or noisy areas of the image will start stacking and will “grow” in relative ISO in multiples. It’s confusing, but tone Mapping will often take little bits of grain and stray light, and treat them as fine details. And, since HDR is all about enhancing those details, you get what you get!

Here are two HDR photos with much noise in the sky:

The most important trick here is to reduce your ISO to as low a level as possible. Use a tripod, and try to get as clean a shot as possible. But keep in mind, using long exposures will also generate noise. We’ve got to find that happy medium. Shooting a scene with 3 brackets at 100 ISO will leave you with a much cleaner image than when shot at 400 or higher.

You’ll want to shoot enough brackets at as low an ISO as possible to properly capture every detail in the scene. This means in a lower light or very high contrast situation, you’ll want to shoot more than just 3 exposures. Typically we’ll shoot at least 5 in these situations and we’ll set the EV to +/- 1 step. This means very subtle differences from exposure to exposure, but we’ll have a lot better information in the selection of RAW files for Aurora HDR to work with.

Watch your blues! Digital camera sensors have a strange quirk about them where they are about 50% less sensitive to Blue Channel light than Red and Green. This means that Blue sections have to be enhanced or amplified to be exposed correctly compared to the reds and greens. 

Since blues will often be darker than the other areas of your image, and more dark = the more noise when brightened. This is the reason why your skies tend to be super noisy when you merge and enhance a landscape image with HDR. As mentioned above, it’s super important to expose properly for every step possible to help reduce these noise situations.

Create an HDR image in Aurora HDR Pro:

Create a new layer and select one of presets, here we have a Dramatic preset:

What’s a way to help reduce the amount of noise in our blues and overall? You can use Noise Reduction before hand. Aurora HDR has a built in, and absolutely incredible denoise tool, but if you’d like to take matters into your own hand first, you can use Noiseless or other Noise Reduction options before you merge your brackets. Just remember to not overdo it and use an app where you can apply your noise reduction in selected areas.

TIP: Use the ZOOM tool when you’re applying noise reduction. Why? Well, noise reduction tools have a tendency to completely smooth out and soften your images. This will pretty much ruin an otherwise incredible photograph and make it look like a cartoon or painting rather than a super cool landscape scene. When you zoom in, you can see precisely how the noise reduction is taking hold of your image and you can adjust accordingly. 

One of the great things with Aurora HDR is its ability to use layers and masks. We can apply noise reduction to an entire layer so the area we want looks great, and then paint it in selectively to ensure the rest of our image still looks sharp and fantastic.

Here's how we can adjust noise reduction selectively:

And here we have a smooth and denoised sky and a sharp water and grass:

Remember that while Aurora HDR comes loaded with an absolutely fantastic noise reduction tool called HDR denoise, you can work with the NR tools found in Noiseless to complete your image with much more power and control. Either way, the key to remember for perfect HDR images is to plan ahead and shoot with as low an ISO as possible!

What Are Layers? - Via Macphun

Here's another from my series of Educational blogs with Macphun!  Be sure to check them all out on https://aurorahdr.com/blog


First, what are Layers?

As the team at Adobe said: “Layers are like sheets of stacked acetate. You can see through transparent areas of a layer to the layers below. You move a layer to position the content on the layer, like sliding a sheet of acetate in a stack. You can also change the opacity of a layer to make the content partially transparent”.

To paraphrase, a layer is simply one image stacked on the top of another, 
with the image on top being visible above of the layers below it.

Here are the reasons to work with layers

  • Layers provide you a non-destructive form of editing
  • You are working on the top or on the copies of your original image
  • You get so much more control of your image
  • You can change the opacity of any effects
  • You can add layer masks to work selectively with the adjustments
  • You can add/work with Luminosity Masks on new layers
  • You can add Texture Files or even load source files from your HDR Stack
  • You can use blending modes to change the way layers interact

Blending modes. Explained.

Change these to adjust the way the selected
layer blends (or displays) with the layers below it.

  • Normal: blend modes will display your image exactly as shot
  • Overlay: combines Multiply and Screen blend modes
  • Hard Light: combines Multiply and Screen blend modes
  • Soft Light: it is a softer version of Hard Light
  • Screen: inverts both layers, multiplies them and inverts the result
  • Multiply: simply multiplies each component in the two layers
  • Color: divides the inverted bottom layer by the top layer, and then inverts them
  • Luminosity: preserves the hue and chroma of the bottom layer

When to use layers?

The short answer - all the time! As a photographer who is passionate about your final result, it’s in your best interest to always use a nondestructive editing method. This allows you to go back to any step of your editing and make safe adjustments, or even revert to your original image with just a single click of a button.

For the safest and cleanest workflow, we recommend making every new change on a different layer to control your image. As you can see from the gallery, every change we’ve made has been done on a new layer. By clicking the "+" icon on the top of the layer section, you can add up to 14 layers with the PRO version of Aurora to work on.

If desired, for each new layer we can create a very selective editing process. As an added bonus, using layer-masking techniques, we can apply very powerful and intense edits to selective regions of our image. We can even apply a texture to the whole image or just a selective area. In the image below, we applied a texture only to the sky.

How to create layers?

To use layers in Aurora HDR, you simply have to hit the "+" button on the top right of the side toolbar in the layer section. Add up to 14 in Aurora HDR Pro, and if you make a mistake, or decide you don’t need it anymore, you can remove the layer by hitting the "-" button. 

When the layer is a lighter gray shade than others, you know it’s selected and anything you do is operating only on that layer. Change the Opacity of the layer by simply clicking the opacity drop down slider and adjust it to your liking.

Layer mask revealed

The next powerful tool hidden within Layers is the ability to use Masks! A mask is simply an area that you select telling Aurora HDR that any edits should only be applied to that area. 

Masks are enabled at 100% by default, but by selecting the brush tool you can also paint in selective edits to your image. By default, the masking brush is set to a 50% opacity, but you have the control to change this from 1% to 100% and the amount of feathering!

For example, you might want a foreground to be highly detailed while the sky remains somewhat soft. Simply create a new layer, brush the mask into the foreground to define an area for your enhancement, and then add details using the Structure or Detail controls on the Adjust panel. Experiment on your own images to see how Brush opacity and feathering work.

Luminosity masks

Luminosity masks are very special masks that are automatically created by Aurora HDR. When you create a new layer and choose “Create Luminosity Mask” from the layer menu, the software makes a mask that separates light and dark tones in the image and preserves their relative strength. When you apply effects to a Luminosity Mask, the enhancements are more pronounced in the light areas of the image.

For more information on working with layers and masks, check out the videos in our gallery. Happy Editing

Understanding Tone Mapping - Via Macphun

Here's another from my series of Educational blogs with Macphun!  Be sure to check them all out on https://aurorahdr.com/blog


What's the first image that pops into your mind when someone says HDR? For most people, they think of dark, grungy, over-saturated images with halos surrounding every hard edge in the photo. The truth is, that's not actually HDR, but in fact, a form of Tone Mapping.

Understand HDR first!

To understand Tone Mapping we need to first explain HDR. So what is HDR exactly? Well High Dynamic Range images simply mean that the photo has more dynamic range in it than any camera (currently) can capture in one single shot. To be able to create a real HDR image, you have to take 3 or more photos at different exposure values. 

 

Typically one frame will be at a proper exposure, then the rest are overexposed and underexposed at various increments to let you capture the details in the brightest highlights and the darkest shadows. Then these images are merged together to create a 16-32 bit file.

As I've explained in a few other blog posts and videos on our YouTube channel, most every camera available on the market currently has a sensor in it that can record information with a very specific dynamic range, (somewhere between 5-14 stops of light), which is FAR LESS than what the human eye can perceive. Therefore we combine these bracketed exposures together to create an HDR image.

If you try to take a high contrast shot with a single exposure you typically end up with either completely blown highlights, or all details lost in the shadows.

When you've taken a proper mix of exposures (under, balanced, and over), and merged them with an HDR software app, you're left with a relatively flat and low contrast image. This is where tone mapping comes into play.

What is tone mapping?

It's the process of converting the tonal values of an image from a high range to a lower one. For instance, an HDR file merged from multiple images with a dynamic range of 100,000:1 will be converted into an image with tonal values ranging from around 1 to 255.

Why do we want to reduce that tonal range so much? Well the reason is simple. Most standard display devices (and printers) can only reproduce a low range of dynamic values (between 100 or 200:1 or lower). The goal of tone mapping is to reproduce the appearance of images having a higher dynamic range to fit/display properly on standard display devices, thus keeping the image looking realistic.

The algorithms that tone mapping use to scale the dynamic range down attempt to preserve the appearance of the original image captured by breaking the information up into two categories: global and local.

Global operators map each pixel based on it's intensity and global image characteristics. The process ignores its spacial location or if it's in a dark or light area. Using global only tends to leave you with a flat non-contrasty image after the conversion process.

Local Operators uses the pixels location in the image when analyzing the appropriate scaling for it. This allows each pixel of a given intensity will be mapped to a different value depending on whether it's found in a dark or light area. Local tone mapping requires the system to look up surrounding values for every pixel mapped. This makes it slower (and more memory/system intensive), but leaves you with a much richer and eye pleasing image when correctly done.

Does shooting in RAW matter?

Short answer - YES! While you can still get amazing images from JPGs, tone mapping using RAW files provides much much much more information for the HDR program to work with. While it may take longer to process, you'll be left with a much more accurate image when working with RAW.

When using Aurora HDR to merge your brackets, you're given one of the most human-realistic representations of the scene possible, and when using raw files, you have a TON of information and tools within your 32-bit image to generate a finished photo with the exact look and feel that you desire!

The reality is, you don't need multiple exposures to tone map your image. You can have a single frame and create just as epic and breathtaking details, however, you will have less dynamic range to play with so remember that.

This is why Tone Mapping and HDR are not the same thing! To create an HDR image, you need at least 2 bracketed images. It boils down to availability and style. It's up to you to create an image that's either realistic, or fantasy like.