miércoles, 23 de noviembre de 2011

Learn Photoshop Sharpening Techniques

Sharpening in Photoshop enables you to select the precise amount of sharpening and the areas of the image that require sharpening most. The actual amount of sharpening required for optimum image quality is usually a little more than looks comfortable on screen even if you are using a TFT monitor.

With the help of Photoshop Techniques, we will learn about sharpening the eyes of a portrait excluding the skin texture.

The best sharpening techniques are those that give priority to the important areas for sharpening and leave the smoother areas of the image well alone. Hence let the project begins.

It is important to switch sharpening options (if any) off or set them to minimum or low in your capture device. Most of the capture devices have the sharpening features that are often very crude when compared to the following technique.

You do not need to sharpen images that have been saved as JPEG files using high compression/low quality settings. The sharpening process that follow must also come at the end of the editing process, i.e. adjust the color and tone of the image before starting this advanced sharpening technique. Decrease the levels of sharpening later if it proves too much.

First Technique: High Pass

1. Copy the background layer and set the blend mode to Overlay. Select 'Overlay' from the blend modes menu in the layers palette.

2. Go to Filter >> Other >> High Pass. Raise the pixel radius until you achieve the correct amount of sharpening. Set pixel radius of 1.0 if printing to Gloss paper and 3.0 if printing to Matte paper.

3. Choose the Foreground color swatch in the Tools palette for opening the Color Picker. Enter 0 in the Hue and Saturation fields and 50% in the Brightness field to choose a midtone grey. Select OK. Paint the High Pass layer to remove any sharpening that is not required, like skin tones, skies etc, as High Pass technique is useful for limiting the visual appearance of noise or film grain.

4. Remember the settings you have selected are being viewed on a monitor as a preview of the actual print. In order to complete the process it is important to print the image and then fix on whether the image could stand additional sharpening or whether the amount used was excessive. If the settings are extreme, choose to lower the opacity of the 'High Pass' layer. Then again switch the blend mode of the 'High Pass' layer to 'Soft Light' to reduce the sharpness or 'Hard Light' to increase the sharpness.

Saturation and sharpening

Most techniques to increase the contrast of an image will also have an unforeseen effect of increasing color saturation. Since the High Pass and Unsharp Mask filters both raise local contrast there is an extended technique if this increased color saturation becomes tricky. Be aware of color fringing after you apply the High Pass technique. Do consider the following technique to limit its effects.

Second Technique: Unsharp mask/Smart Sharpen

The second technique address the issues of increased saturation leading to the effect of color fringing. If a merged layer is used as the sharpening layer and then changed to Luminosity blend mode the effects of saturation are removed from the contrast equation. This technique looks how the benefits of localized sharpening and Luminosity sharpening can be combined.

1. Adjust the Blend mode of the High Pass layer back to Normal mode. After that, apply a Threshold adjustment to the High Pass layer. Select Image > Adjustments > Threshold.

2. Pull the slider just below the histogram to isolate the edges that require sharpening, in order to render all of those areas you do not want to sharpen white. Click 'OK' when you are done. Paint out any areas that were not rendered white by the Threshold adjustment that you do not what to be sharpened.

3. Choose the Channels palette, either Ctrl-click (Windows) or Command-click (Mac OS) the RGB thumbnail or click on the 'Load channel as selection' icon from the base of the channels palette to fill the edge detail as a selection. Go back to the layers palette and pull the Background layer to the new layer icon to make a background copy layer. Pull this background copy layer to the top of the layers stack.

4. Turn off the visibility of the High Pass layer. Press down the Alt or Option key and click on the 'Add layer mask' icon in the layers palette. Make sure that the layer mask thumbnail is the active part of the layer and then choose Filter > Blur > Gaussian Blur. Set 1.5-pixel radius blue to the mask.

5. Click on the image thumbnail on the background copy layer. Make sure the image is zoom in to 100% for a small image or 50% for a larger print resolution image (200ppi - 300ppi). Select Filter > Sharpen > Smart Sharpen or Unsharp Mask. Adjust the Amount slider between 80-150% to control that how much darker or lighter the pixels at the edges are rendered. Prefer an amount slightly more than looks comfortable on screen if the image is destined for print rather than screen.

It is recommended to see Capture and Enhance for basic settings of the Unsharp Mask filter. The accurate Threshold and Radius settings are not so critical for this advanced technique.

6. Transform the blend mode of the sharpening layer (the uppermost layer) to Luminosity mode so that it will restrict the contrast changes to brightness only, and will eliminate any changes in saturation that have occurred due to the use of the Unsharp Mask. Use this technique only when you are aware about problems of color fringing due to increased saturation.

See yourself the effects of changing the blend to Luminosity. These two techniques are capable of producing razor sharp images that will really put the final changes to a folio quality image.

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