Say bye to Noise

Say bye to Noise

Breathe new life into grainy pictures shot in low light.

By Anand Tuliani

Digital cameras have progressed by leaps and bounds in terms of features. The latest models are compact and offer useful features such as wide-angle lens and smile detection that make photography fun. Also latest-generation image sensors and image processing engines deliver spectacular results even in low lighting conditions. However, despite these advancements the toughest challenge for digital cameras is dealing with noise. Shoot a photo outdoors in broad daylight and you’ll get crisp details and rich colors. But even digital SLR cameras come to their knees when the ISO (sensitivity of the image sensor to light) is boosted in order to get well-exposed shots in poor lighting. The image sensors used in digital cameras are diminutive in size—as tiny as the nail of your pinky finger. Now imagine 12 million pixels packed into that much space. This immense pixel density is the reason why digital cameras produce excessively noisy results in low light. In contrast to compact digital cameras, digital SLR cameras have bigger sensors (as large as a postage stamp) due to which the results are way better. But then bigger sensors require larger and more complex optics, which make digital SLR cameras bulky. Compact digital cameras require smaller lenses with shorter focal lengths for greater zoom ratios.

When shooting in broad daylight or good lighting, the ISO is lowest (at around 80 or 100). But the digital camera boosts the sensitivity to 400 or 800 in low light. This causes grainy artifacts that ruin the images. Some cameras are equipped with a noise reduction function to reduce the effect, but yet the results aren’t satisfactory. Here’s how you get rid of noise.

– anand.tuliani@chip.in

curing grainy photos in THREE SIMPLE STEPS

STEP 1: Noise Ninja is one of the top-rated and easiest tools for curing noisy images. It’s available as a Photoshop plug-in as well as a standalone application at www.picturecode.com. On opening the image in Noise Ninja the Noise Profiler section will show up in the left pane. Click and drag patches on plain areas of the image that don’t have any detail. Avoid regions that are pitch black or over-exposed. The software uses these samples to calculate the values for noise removal in the next step. Use the scroll wheel to zoom in/out. The image can be dragged around using the left mouse button while keeping the spacebar pressed.

STEP 2: Click the Noise Filter button (with the magic wand icon) when you’re done with profiling the image. Noise Ninja automatically determines the values for luminance, colors and sharpening. Clicking anywhere on the image shows the output preview of that portion in a small box with dotted lines. Zoom into the image and drag the box around to preview the various portions. If noise persists, increase the luminance strength by dragging its slider. But be careful not to overdo it as it will result in loss of details. The ‘Show advanced controls’ options allows you to adjust even the smoothness and contrast.

STEP 3: After you’re done with adjusting the noise filter parameter and previewing the result, the final step is applying the filter and saving the image. Click the Remove noise button to apply the filter. The result can be saved in JPG or TIFF format. Before saving the image, you have the option to set the image quality of JPG and color depth.

PROCESSING MULTIPLE IMAGES:

If you have hundreds of image to process, you can use the Batch Process function in the File menu. In that case, you can tell the software to profile the images automatically before applying the noise filter. You can also create profiles for different ISO levels for your camera by referring to the built-in user guide. If you have a dual-core or a quad-core CPU, you can speed up batch processing by specifying the number of working threads in ‘Edit | Preferences’