Digital Work Flow pt.1 Tutorial


Part 1- Initial backup and sharpening

After you have captured those wondrous moments in time called images you rush home to download and save the "keepers" to your hard drive. Only later when you are ready to work with the images you discover that a virus has obliterated your hard disk! Back up your files as soon as you pull the raw images out of the camera. This keeps an unaltered copy for later use. Label and store these images away into a long term storage container. I generally buy several 200 CD jackets when they go on sale at W*lm*rt or T*rg*t (that's all they get until they pay for endorsements) for around $15 each. Be descriptive in your labels I write the date, location, numbers of files I index these to a spread sheet where I can add extensive comments about any additional information (camera and settings), like any particular photos I may need to reference later (PICT0023- Pelican for postcard). Any good spreadsheet program will let you sort and search your archives and content.
The next step is to duplicate the images again to a "working folder" and begin the first level of correction.

Level 1 - Corrective Sharpening - Requires at least Photoshop 5. There's a lot of misunderstanding about when and how to apply sharpening. I find it useful to break down sharpening into three general categories: Corrective sharpening, which compensates for blurring from either the camera or lens. Creative sharpening, which you apply to a specific part of an image and not another (eyes, but not Crows Feet). Output sharpening, which is based on where you plan on the image's final output destination (print or web, postcard or billboard). In this installment We are going to cover Capture sharpening and neutral color correction (this assumes you want to get rid of a color cast).

I have found after working with several digital cameras that the CCDs suffer from some loss in contrast which holds the same from photo to photo, some cameras more than others especially in cameras that are more than 3 years old. CCD technology has changed significantly over time and the new sensors far exceed their predecessors of even 18 months ago. None the less, even the newest technology still benefits from some sharpening. The following procedure can and should be recorded as an action script as this corrects inherent and unique and reoccurring issues with your camera, if you use different cameras you should create a separate script with unique settings for each.

For this tutorial you will need at least Photoshop 5 and an uncorrected photo with a good range of textures and contrasts and in need of some color correction (or you can download the sample photo from here). The sample photo is of some granite rocks at John's Pass. There is plenty of texture in the photo but by comparison to what was actually there the image seems flat and boring. Part of the trick to sharpening an image is to avoid producing color halos around objects in the picture. Even a light amount of the Unsharp Mask filter will cause some haloing of the colors in the photo. To reduce haloing we will remove the colors from the problem.

Step 1) Convert the file to LAB color space (Image>Mode>LAB Color). This will separate the color information from the light and dark information. LAB creates color channels A and B and a separate lightness channel (fig 1).
Step 2) In the Channels Pallet choose the lightness channel (fig.2) and apply a light amount of the unsharpen mask(Filters>Sharpen>Unsharpen Mask) with starting settings of Amount=100% , Radius=1.0 ,Threshold=0. Click apply (fig.3). and switch back to RGB mode (Image>Mode>RGB). The channels pallet will switch back to RGB (fig.4). Experiment with the settings till you are satisfied with the result, try different "Amount" settings of less than 100% to reduce the lighter halo, more than 100% to increase texture.
Step 3) Save the file as a PSD and proceed to color correction.

This tutorial assumes that you have already color corrected your monitor for use with Photoshop. The first problem in color correction is in Photoshop's own default Eyedropper settings that we must correct first. In nature true black and white are never pure black and pure white but a mixture of the spectrum. By adjusting Photoshop's Eyedropper white point, black point and gray point we will get a more realistic color correction. Open the sample image from the previous tutorial.

Step 1) Change the setting of the eyedropper tool from 1x1 pixel to 3x3 pixel average sample by selecting the Eyedropper from the Tool Bar and then up in the Options Bar change the setting from "Point Sample" to "3x3 Average" (fig. 5). Single pixel sampling is inaccurate for use with most photos.

Step 2) Open the "Curves Pallet" (command or control M). Start by dbl clicking on the black filled eyedropper on the bottom left of the "Curves Pallet" (fig. 6). A color picker box will open enter 10 in the R, G and B boxes. Click OK in the Color Picker box (fig. 7). Now dbl click on the white eyedropper in the "Curves Pallet" as before enter these settings R, G and B boxes 244 and click "OK" as before. Now the dbl click the gray eyedropper and enter settings 133 in the R, G, and B boxes and click "OK". Click "OK" in the "Curves Pallet" a message box, "Save the new target colors as defaults?" click "Yes" (fig. 8). Now we are ready to begin.
Before we begin the next step I find some quick clarification is in order. We will be using the "Threshold" adjustment layers but not ever creating them (not clicking OK) and once you select the "Color Sampler" tool do not select a different tool.

Step 3) Go to the "Layers Pallet" and create a "Threshold" adjustment layer (fig. 9, 10, 11). Move the slider all the way to the left so that the image turns completely white. Slowly move the slider back to the right till the first small areas begin to turn black. These are your whitest points. Click the "Eyedropper"tool and set your first target in the first bit of black you see that is at least 3x3 pixels wide by clicking the area with the "eyedropper" tool while pressing the shift key.This will leave a numbered target marker. Run the slider all the way to the right to make the image totally black. Slowly move the slider back to the left till the first small areas begin to turn white. These are your blackest points. Set your second target in the first bit of white you see that is at least 3x3 pixels wide. Click "CANCEL" in the threshold adjustment box. You will still see the previous two targets you made with the "Sampler Tool".
Now for the neutral gray (without guessing!). In the "Layers Pallet" create a new empty layer above the background layer. Fill this layer with 50% gray (Edit>Fill and choose 50% gray from the "Fill with" drop down and opacity of 100%). Click "OK". In the "Layers Pallet", set the "Blend Mode" of the new layer to "Difference". Again, create a "Threshold" adjustment layer. Drag the slider to the left till the image is all black, slide to the left till the first white begins to show. Place your third color sampler target in the first 3x3 white area that shows this will be the true mid-tone gray area in your photo. Click "CANCEL" to abort the adjustment layer then delete the gray layer you created, you should see all 3 targets on your photo.

Step 4 ) Now the corrections. Now open the "Curves Pallet" (ctrl/cmd-M). Select the white eyedropper from the lower left of the "Curves Pallet" then carefully click on the first target (the White Point) you create in the previous steps. Then choose the black eyedropper and click on the second target you created from before (the black point) and finally the gray eyedropper to the third target.

Stay tuned for further tutorials on cosmetic sharpening and other useful special effects.

AddThis Social Bookmark Button

fig.1) LAB color channel pallet

fig.2) Lightness channel

fig.3)unsharpen mask control pallet

fig.4) RGB channels

fig.5) Eye dropper options pallet

fig.6) W,B,G point adjustments

fig. 7) Color picker

fig. 8) Save color balance changes

fig. 9) Adjustment layers

fig. 10) Slide left

fig. 11) Slide right

fig. 12) Setting the whitest point

fig. 13) New layer and blend mode

fig. 14) Fill with 50% gray





Michael S Richter © 2000 - 2011 ALL RIGHTS RESERVED