Pick N` Mix For Lovers Of Dynamic Detail

Transcript

Pick n’ Mix for lovers of dynamic detail For those who like to have their cake and eat it, Mark Galer introduces a two into one postproduction editing technique to extract all of the detail from your information rich RAW images. Fig 00a. Unleash the detail from your camera RAW files and enjoy extended dynamic range Are your images suffering from the black hole syndrome? You take a picture of a sunrise or sunset and the immediate foreground is a silhouette with little if any detail. If you increase the exposure to rescue detail in the foreground you then loose the sky to overexposure. Although your eye can register detail in both the highlights and the shadows the image sensor of the camera is seriously challenged in these situations. The contrast of the scene is said to exceed the dynamic range of the image sensor. There is however hope – and it lies in the ability of the camera’s sensor to record a broader range of tones than are usually rendered or processed to the JPEG file format in the camera. Dynamic Range is the ability of the camera’s image sensor to record the subject’s brightness range from the deepest shadows to the brightest highlights. The greater the dynamic range of the sensor, the broader the range of tones that can be recorded. The large image sensor’s found in typical digital SLRs can capture a broader range of information than the digicams using smaller sensors. This broad dynamic range however, can usually only be accessed if the DSLR owner switches from the JPEG file format to the camera RAW format in the camera’s quality menu so that the information is processed by Photoshop rather than by the camera. Note > If you have a new Digital SLR you may need to download a camera RAW update for either CS2 or Elements 4.0. If the software’s RAW plug-in is older than your camera then Photoshop will not be able to recognize the RAW files from this new camera. The most recent camera RAW plugin is 3.3 and supports recent models such as Canon’s 5D, Nikon’s D200 and the Olympus E-500. To access the latest plug-in go to http://www.adobe.com/products/photoshop/cameraraw.html Fig 00b Use the exposure slider in the camera RAW dialog box to increase either the highlight detail or the shadow detail When the RAW file is opened in Photoshop Elements or Photoshop CS2 the exposure slider in the camera RAW dialog box allows the user to choose an increased or decreased exposure setting from the one that was selected in-camera and used to capture the image. This allows the photographer to access either increased highlight information or increased shadow information after the image has been captured. When the image is opened in Photoshop’s editing space the RAW file closes and a copy of the file with your preferred exposure setting is opened into the main editing space of your Photoshop software. Note > When the RAW information is processed the preview and thumbnail of the RAW file reflects these preferences but the RAW data cannot itself be modified. This RAW file can be processed a second time with a different set of preferences for exposure, color and tone. Fig 00c. The same RAW file can be processed twice to achieve optimum highlights and optimum shadows To achieve the optimum dynamic range that is possible from the information recorded by the image sensor (increased shadow detail AND increased highlight detail) we can open two images from the same RAW file, each file being optimised for a different end of the exposure range. In Photoshop we can then simply merge the two exposures together. Some would call this manipulation when in reality all we are doing is restoring the tonality back to how our human vision first saw the scene rather than how the camera interpreted it. Fig 01. Open your camera RAW file in the Adobe Camera RAW dialog box 1. Open your camera RAW file in the Adobe Camera RAW dialog box. Move the Exposure slider to the right until the shadow detail has opened up and the detail is clearly visible. Pay no attention to the highlights that will now be overexposed. If you have the Shadows and Highlights boxes checked the color red indicates that massive amounts of highlight detail is being lost or ‘clipped’. Notice however how the tall peaks on the left hand side of the histogram move away from the left side as you move the exposure slider to the right. If the shadows are rich in detail but appear flat and grey you can compensate for these by raising both the Contrast and Saturation sliders. Zoom in to 100% and check the shadows for excessive noise. If noise is a problem proceed to the Detail tab and raise the Luminance Smoothing and Color Noise Reduction sliders to the right until the noise is sufficiently suppressed. Set the Depth in the lower left hand corner of the dialog box to 8 Bits/Channel and select Open. Fig 02. Save and name the file 2. The first file will now open in the main editing space and the RAW file will close with your settings saved. Before opening the master RAW file into RAW dialog box a second time it is important to save and rename the first file otherwise Photoshop Elements will be confused as to why you want to open the RAW dialog box a second time when you have already processed an image that is still open in your editing space. Fig 03. Optimize the settings for the highlights 3. When the RAW file opens in the RAW dialog box for the second time you can now move the exposure slider to the left to optimize the image for the highlight detail. Choose an appropriate setting for the Contrast and Saturation sliders and again select the ‘Open’ button. Note > In the example some highlight clipping remains even with an exposure setting of -1.75. If you are presented with this scenario the only way of achieving additional information is to bracket the exposures whilst the camera is mounted securely on a tripod during the initial capture. Fig 04. Combine the two exposures in Photoshop’s main editing space 4. Now that you have two files opened from the same camera RAW file you can start to combine the best aspects of each exposure. Start the process by selecting the darker image and then dragging its thumbnail from the layers palette into the image window of the lighter first image. Hold down the Shift key as you let go of the thumbnail to ensure that both exposures are perfectly aligned. Fig 05. Create a layer mask for the purpose of merging the two layers 5. The next step involves adding a layer mask. Users of the full version of Photoshop can simply select the top layer and then click on the Add layer mask icon in the Layers palette. This procedure is off-limits to users of Elements so they must instead add an Adjustment Layer and use its accompanying layer mask instead. To create an adjustment layer for this purpose first select the ‘Background’ layer in the Layers palette and then click on the Create adjustment layer icon and choose Levels. Do not make any adjustment in this dialog box but simply select OK. Fig 06. Elements users must group the top image layer with the adjustment layer to use its layer mask 6. Photoshop Elements users must now Group the top layer with this adjustment layer to link the layer mask to this image layer. Click on the top layer to make this the active layer and then from the Layers menu choose Group with Previous. Fig 07. Select the gradient tool and options 7. In the Tools palette choose The Gradient Tool and from the Options bar choose the Black, White gradient, Linear option with an Opacity of 100%. Click on the layer mask to make this the active component of the layer. Fig 08. Add a linear Black, White gradient to the layer mask to merge the two exposures 8. Move the cursor into the image window and click just below the horizon line. Hold down the Shift key and drag the gradient to a position just above the sun and then let go of the mouse clicker. This action will add a gradient to the layer mask and will act to hide the darker foreground pixels in the top layer. We will now be able to view the sky from the image with the decreased exposure and the foreground from the image with the increased exposure. Note > A more complex mask is often called for when the subject is not so clearly defined as a bright sky and a dark foreground. If this is the case you can paint directly into the mask using a softedged paintbrush with the foreground color set to black and the opacity dropped to 50%. Fig 09. A duplicate layer in overlay mode is used to increase the contrast and saturation of the sky 9. To create the right balance between the foreground and background it may be necessary to finetune the image. We could have increased the contrast and saturation of the decreased exposure in the RAW dialog box but it was difficult to gain an idea of what the two images would look like when combined at this stage of the process. In this project it was decided to duplicate the top layer and switch the mode to Overlay (drag the layer to the new Layer icon in the Layers palette). You will notice that the duplicated layer is still part of the group and so the mask shields this layer as well as the layer beneath. The Overlay blend mode has the effect of increasing both the contrast and the saturation of the sky. The effect is that the image now looks like how I remembered the scene when I first raised the camera to my eye. Fig 10. The layers are merged and the resulting layer sharpened for printing 10. To complete the project the image can be sharpened. As the image is now the result of pixels on three different layers the image must either be flattened or alternatively, the information from the three layers can be merged and pasted into its own layer. The keyboard shortcut that makes this an easy affair is to hold down the Ctrl+Alt+Shift modifier keys and then type the letter E (CS and Elements 3 users must type the letter N followed by the letter E). The project image was sharpened using the settings Amount:180, Radius 1.5 and Threshold 5. Note > Mac users need to hold down the Command key instead of the Ctrl key.