BEGINNERS’ WORKSHOP

 Layers panel

 When shooting in low-light conditions, using a high ISO, or scanning prints or film, it s easy to introduce noise: black-and-white grain or colored speckles that render the image useless. Sharpening such images only makes it worse. Happily, both Adobe Camera Raw (ACR) and Photoshop do a good job of sending noise packin .

Camera Raw lets you reduce noise across the whole image (globally) and, new in Camera Raw 7, selectively (locally) by using the Adjustment Brush. Both methods are covered here. If you re shooting in RAW format, this is the best place to nix noise.

ACR: GLOBAL NOISE REDUCTION

step one Open an image in ACR by double-clicking its icon.

Open the Detail panel (circled) and locate the Noise Reduction section toward the bottom.

 Layers panel

step two: Set the zoom percentage to at least 100% by pressing Command-Option-O (PC: Ctrl-Alt-0) and then drag the Luminance slider rightward to reduce grain. To preserve detail, drag the Luminance Detail slider rightward (not too far or you ll introduce artifacting or blockiness). Some color noise reduction happens automatically but you can increase it to remove more specks by dragging the Color slider farther rightward, and then use the Color Detail slider to maintain detail.

step three Click Done to apply your changes, which are editable the next time you open the image in ACR. To open the image in Photoshop, click Open Image.

ACR: LOCAL NOISE REDUCTION step ONE: Press K to grab the Adjustment Brush and then press Y to turn on the Show Mask checkbox, enabling you to see brushstrokes as a white overlay as you paint. Press M to turn on the Auto Mask checkbox to limit your brushstrokes to pixels similar in color to the ones you paint across.

step two: Paint across the noisy parts of your image. To change brush size (indicated by a solid line), use the Size slider or Right-click-and-drag left to decrease, and right to increase. To adjust feather amount (indicated by a dotted line) so the adjustment blends well with surrounding areas, use the Feather slider or Shift-Right-click-and-drag left to decrease, and right to increase. To erase brushstrokes so the adjustment won t happen in that area, Option-drag (PC: Alt-drag) to put the tool in Erase mode. When the mask is finished, press Y to turn its visibility off.

step three Drag the Noise Reduction slider rightward until the noise is gone. Press P to toggle the image preview on and off to compare this version to the original.

 Layers panel

REDUCE NOISE IN PHOTOSHOP Nestled snugly in the Noise subcategory of the Filter menu lies the noise-reducing filters in Photoshop. The Reduce Noise filter is particularly handy as it gives you some nice control.

step one: Choose File>Open as Smart Object and navigate to the image you want to adjust. Either way, Photoshop creates a smart object, enabling the filter to run nondestructively.

step TWO: Choose Filter>Noise>Reduce Noise and in the resulting dialog, increase the zoom percentage to at least 100%. Drag the Strength slider rightward to reduce grain. If you lose detail, drag the Preserve Details slider to the right to reduce the amount of grain Photoshop removes. It requires experimentation to find a nice balance of detail preservation and noise reduction. Drag the Reduce Color Noise slider rightward to make Photoshop zap more colored specks if necessary. Press P to toggle the preview on and off to compare versions while the dialog is open.

step three: Noise-reducing filters work by blurring pixels and the Sharpen Details slider brings back some of the original sharpness. However, it s usually best to set it to 0% and sharpen using the Unsharp Mask or High Pass filters.

Tip: The Advanced radio button lets you tweak each color channel individually. For example, grain is notoriously bad in the blue channel. To preserve maximum image detail, you can reduce noise in that channel only. Click the Per Channel tab and pick Blue from the Channel pop-up menu. Adjust the Strength and Preserve Details sliders until the grain disappears.

step FOUR: Click OK to run the filter. Click the visibility Eye icon to the left of the Reduce Noise filter in your Layers panel to see a before and after image. To tweak the Reduce Noise settings, double-click the filter in the Layers panel to reopen its dialog. Tip: You can also use the Smart Filter s mask —-the white thumbnail beneath the image layer in your Layers panel —to hide the noise reduction from certain areas. To do it, click the mask to activate it, press В to grab the Brush tool, press X until your Foreground color is set to black, and then paint across that area.

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