PHOTOGRAPHY
Discover why jagged edges and pixelated patterns appear on certain textures in digital photography, and learn effective ways to prevent them during shoots or correct them in editing.
Sometimes called moiré or a glitch, aliasing is a phenomenon where a digital camera has trouble translating an intricate pattern. This can result in various visual distortions, such as strange waves or swirl patterns over finely striped or patterned surfaces. These effects, known as moiré patterns, can also cause colour noise, tone jumping, or jagged edges, often called "jaggies."
“Aliasing is basically an artefact that makes an image look particularly digital in a disagreeable way,” says photographer Philip Heying. “It’s caused when digital information is broken down into pixels and bits; little tiny particles that are laid out in a grid. Sometimes, when information that you’re seeing in the real world meets that grid of the digital world, it’ll cause this objectionable moiré pattern or strange colour shift that doesn’t look like what you’re seeing.”
In Australia, aliasing can be a significant challenge, especially for architectural photographers. The intricate patterns on the Sydney Opera House sails, for example, can cause moiré effects if not captured carefully. This issue also extends to other detailed structures and patterns found in Australian cityscapes and landscapes, such as the geometric designs of modern buildings in Melbourne or the lattice work of the Story Bridge in Brisbane. Additionally, the vibrant and varied textures found in Australia's natural scenery, from the unique rock formations in the Outback to the intricate foliage in rainforests, can also present aliasing challenges. Photographers need to be particularly vigilant in these scenarios to avoid unwanted visual artifacts in their images.
Anti-aliasing encompasses a range of techniques used to minimise or eliminate the visual distortions caused by aliasing. In digital photography, anti-aliasing helps smooth out jagged edges and pixelated patterns, resulting in cleaner, more accurate images. These techniques are essential not only in photography but also in fields like graphic design and video games, where precise image rendering is crucial.
Anti-aliasing techniques are used across various digital fields, including photography, graphic design, and video games, to smooth out the jagged edges and reduce visual distortions caused by aliasing. High-quality anti-aliasing is essential not just in photography but also in computer graphics and video games, where it helps process complex scenes into lower-resolution images.
Read more: How to smooth out aliasing in graphic design.
Aliasing typically appears in photos with highly detailed patterns, such as stripes, checks, and grids. It's less common in landscape or nature photography but can be a major concern in architectural or fashion photography. “I did architectural photography for a while and I would encounter it every now and again on a roof or the side of the building,” says photography professor Adam Long.
To see aliasing in action, try taking a photo of your computer screen with your phone. The resulting image will likely show moiré patterns, demonstrating how aliasing occurs.
Australian wildlife photographers can also face aliasing issues when capturing intricate natural patterns, such as the stripes of a kangaroo or the feathers of a kookaburra. The camera sensor may struggle to accurately capture these fine details, leading to unwanted moiré effects. This problem can be particularly pronounced when photographing birds with detailed plumage, like the rainbow lorikeet, or the delicate scales of reptiles found in Australia's diverse ecosystems. To mitigate these effects, wildlife photographers must pay close attention to their camera settings and positioning to ensure the natural beauty of these animals is preserved without digital artifacts.
Some cameras come equipped with built-in anti-aliasing filters (Optical Low-Pass Filters or OLPFs) that help reduce detail in fine patterns and prevent aliasing. These filters add a slight blur to the photo, preventing the camera from capturing overly detailed patterns that can cause aliasing. Check out local Australian stores that stock these specific cameras for more options.
Stopping down the lens (using a smaller aperture) can introduce diffraction, which slightly softens the image and potentially reduces aliasing. This technique can be particularly useful when shooting highly detailed patterns.
Changing your shooting position or zooming in can alter how the camera "reads" the pattern, potentially eliminating aliasing. Experiment with different angles and distances to find the best composition.
Resizing an image can sometimes eliminate moiré patterns without sacrificing image quality. This is a simple yet effective method to tackle aliasing.
Using blur filters such as Gaussian blur or the Reduce Noise filter can add a subtle softening effect to the entire image, masking aliasing. This method is effective for reducing visible artifacts.
The Blur tool allows you to apply localised blur to specific areas of the photo, effectively targeting problematic patterns. This tool provides precision in post-production corrections.
Ensure you check for aliasing at different image sizes, especially when resizing for various purposes like printing or web use.
Photographer Philip Heying advises, "Sometimes I’ll make my image on the monitor as small as a postage stamp and then I’ll zoom in 400 percent to make sure all of it is cohesive and coherent. By the time I go to make a print, there are no surprises. Maybe do a test print and see if it’s showing up and how it looks in your print."
Aliasing can affect selections made with tools like the Magic Wand or Quick Selection tool. Be mindful of this when editing to avoid selecting unwanted artifacts.
Mastering aliasing and anti-aliasing techniques can transform your photography, allowing you to capture intricate details without unwanted artifacts. Experiment with these techniques to find the best solutions for your unique shooting situations and watch your images improve dramatically.
We invite you to share your journey and photos on Adobe's community forums. Join a vibrant community of Australian photographers, where you can foster creativity, exchange tips, and find endless inspiration. Dive into the world of composition with Adobe Photoshop and take your photography to new heights. Embrace the challenge of mastering these techniques and witness your skills soar as you create stunning, artifact-free images.
