iTeach Instructional Resources

Photoshop Tips

  • Get the Best Range from your Color Scans
    Many flatbed scanners support 30- or 36-bit color scanning, which captures a larger number of shades per color than older, 24-bit scanners (which capture 256 levels each of red, green, and blue). When the raw scan is loaded into Photoshop, you'll need to convert it to 24-bit RGB before you can retouch it or convert it to CMYK, but first use the Levels tool to set your highlight, shadow, and midtone points to capture the best range of colors in the image. --David Claunch
  • Import Curves into your Scanner's Software
    To get the best color and contrast in a scan, make a low-resolution scan, open it in Photoshop, and make all color and contrast improvements with Photoshop's curves feature. Save the curves and load them back into your scanner's software. Now your scanner will use the color-corrected curves, creating a better high-resolution file as a result. If you're scanning multiple images with a similar color range, you can always save the curves and reload them on demand. This technique is especially helpful when your scanner is set up on a secondary workstation with a smaller, older monitor that makes color difficult to judge. -- Katrin Eismann
  • Get Great Scanned Images
    Many flatbed scanners come with transparency attachments that fit over the top of the scanning bed. For best results with a transparency or slide, remove the image from its sleeve or slide mount and tape it to the glass scanning bed, emulsion side down (the emulsion side is usually the duller one). Cut a mask out of black paper to cover the entire scanning bed except where your art is placed. This will reduce flaring and over-exposure during the scan. Similarly, when scanning 3D objects, cover your scanner's lid with something whose color contrasts with the object you're scanning. That helps you select it with Photoshop's Color Range tool more easily. -- David Claunch and Katrin Eismann
  • Scan Prints without Moiré
    When scanning an image that has already been printed, you may see a moiré pattern from the halftone dots in the image. If your scanner doesn't have a de-screen option, experiment to find a resolution that minimizes the moiré. Often, a resolution equal to or double the printed line screen will work. Once you get a fairly good scan, use Photoshop's Gaussian Blur filter (at a setting of less than 1 pixel) to slightly blur the moiré until it's not visible and then apply an Unsharp Mask to sharpen the image back up. You may also improve the scan by rotating the image slightly, which changes the halftone screen angles. Rotating 45 degrees works well for black-and-white images, but with CMYK images you'll need to experiment. - David Claunch
  • Fade your Color Adjustments
    You probably know that you can reduce the effects of the last-used filter by choosing Fade from the Filter menu in Photoshop (as long as you don't do anything else to the image first). But did you realize that the Fade feature also works on the features in the Adjust submenu in the Image menu? For instance, you can reduce the effect of the last Curves, Hue/Saturation, Levels, or even Color Balance adjustment. If you made the change using an Adjustment layer, this feature doesn't work, but to achieve the same effect you can reduce the opacity for the Adjustment layer. - David Blatner
  • Group Layers and Use as Masks
    In Photoshop you can use the transparency mask from one layer as a mask for a layer above it by grouping the two layers together. Just Option- (Alt-) click on the line that's between the two layer tiles in the Layers palette. This works only if the lower tile has transparency. - David Blatner
  • Optimize Grayscale Images
    Some digital cameras capture images with a noisy blue channel, so if you need to convert a captured color image into black and white, do not choose Mode, Grayscale from Photoshop's Image menu. Rather, select the green channel, then the Grayscale mode. Instead of flattening all the channels, including blue, into the black-and white image, Photoshop discards all channels but green. - Katrin Eismann
  • Calibrate and Ask before you Convert Colors
    Properly calibrate your monitor using the revised Gamma wizard. In the past, I would have characterized Gamma as an optional tool, a nifty way to adjust screen colors but little more. Now, Gamma or some other kind of calibration is mandatory. This straightforward utility generates a ColorSync profile on the Mac and an ICM file under Windows that identifies your monitor. Without this essential information, Photoshop's conversion are likely to be wrong. (If you don't care for Gamma, you can use a third-party calibrator such as Radius's ProSense or the Color Partnership's OptiCal.) Second, you can choose the Profile Setup command from the File, Color Settings submenu and set all three Profile Mismatch options to Ask When Opening. This makes you the judge and jury on all color conversions. When you open a file from the old days, Photoshop will ask to convert it. You can say yes or no. Because Photoshop will actually change the pixels if you say yes, it is imperative that you have the final word. If you decline the conversion, you're no worse off than you were in the old days; Photoshop's display may have changed, but your file has not. - Deke McLelland
  • Preserve Transparency in Drop Shadows
    When you create drop shadows - or whenever you need to fill pixels on a transparent layer in Photoshop - press Option- (Alt- in Windows) Shift-Delete to fill with the foregrund color while preserving transparency. This is better than clicking on Preserve Transparency in the Layers palette, which interferes with additional effects that may be applied, such as running a Gaussian Blur to soften a shadow. - Katrin Eismann
  • How to Cast a Shadow
    Photoshop's Drop Shadow command, one of the program's new layer effects can also be used as the starting point for a cast shadow that can be manipulated independent of its subject. After isolating the subject on its own layer, choose Layer, Effects, Drop Shadow; set the Blur and Intensity to give you the softness and shadow density you want. (Use whatever Distance and Angle settings will give you a good look of softness and density.) You can, of course, apply other effects. Then separate the effects to layers of their own by choosing Layer, Effects, Create Layer. Activate the shadow layer and choose Edit, Transform, Distort to match an existing perspective, exaggerate the shadow's shape, or lay it down on the ground. Drag on the Transform box's handles, and double-click inside the box to finalize the effect. - Linnea Dayton and Jack Davis
  • Use Blur to Remove Specks and Scratches
    To get rid of dust specks and scratches quickly in Photohop, use the Blur tool at 100 percent pressure. Set the Blend mode to Darken to remove light specks and Lighten to remove dark spots or blemishes. - Katrin Eismann
  • Use Arbitrary Maps to Create Unusual Effects
    To create special effects quickly in Photoshop, use the Gradient tool's Arbitrary Maps with a Curves Adjustment layer. First, double-click on the Gradient tool, click on Edit, and select a blend. To save the gradient as a map setting, hold down Command (Control in Windows) while clicking the Save button. Now just add a Curves Adjustment layer to an image and load the arbitrary map. Violà - instant cool effect. By experimenting with the blend modes, more effects can be created quickly. - Katrin Eismann
  • Run Photoshop on Less Ram
    Tired of resetting RAM for Photoshop on the Mac? From the Finder (when Photoshop isn't running) select the application icon and press Command-D to duplicate the application itself. Now use Command-I to set the RAM for each version of the program, taking advantage of most of your computer's total RAM for one version of the application and setting the RAM for the duplicate low enough to allow you to run multiple applications at the same time. Set the duplicate to 30 MB which is enough to view images, crop, and perform other simple tasks. Both versions use the same preferences and plug-ins. Double-clicking on any Photoshop document opens it in the version that is running. - Sharon Steur
  • Switch Lassos on the Fly
    Photoshop's Magnetic Lasso tool is great for drawing a selection that follows a distinct color or contrast boundary. But if the area you want to select doesn't have a distinct color boundary all the way around it, you can switch between the Magnetic Lasso, the original Lasso, and the Polygon Lasso. Start clicking the Magnetic Lasso where you want to start the selection boundary, then release the mouse and float the cursor along the image. When you get to the point where you want to hand-select, hold down Option (Alt in Windows), and click and drag to use the original Lasso. Continue to hold down Option (Alt) and click from point to point to make straight segments with the Polygon Lasso. If you get to a point where you want to follow the color boundary again, release Option (Alt), click on the boundary, and continue to drag or float with the Magnetic Lasso. - Linnea Dayton and Jack Davis
  • E-mail Large Files Efficiently
    You can send large image files across the Internet efficiently by splitting them into channels. The sender simply uses Photoshop's Split Channels command in the Channels palette fly-out menu and e-mails the CMYK channels separately. Name each channel file something, such as Channel_C.tif for the cyan channel, Channel_M.tif for the magenta channel, and so on. If you're receiving the files, you need to join them: Open all four images by dragging them onto te Photoshop application icon. Then in the Channels palatte choose Merge Channels from the palette menu; select CMYK Color from the Mode pop-up menu; and press Return. Make sure that the proper files are assigned to proper channels - C is cyan, M is magenta, and so on (this is where those logical file names come in handy) - and hit Return again. Save the finished image to a separate file, and you now have the complete CMYK. - Deke McClelland
  • Create Dotted Lines with a Custom Brush
    To create a dotted line in Photoshop, start by creating a custom brush. Select New Brush in the brushes palette, set an appropriate size, and set the spacing to 200 percent. Now create a path and stroke it: select any of Photoshop's paint tools and choose the custom brush with the 200 percent spacing. Select the path from the Paths palette and choose Stroke Subpath from the pop-up menu. Choose the paint tool you just selected, and click OK to stroke the path with the dashed line. - Daniel Giordan
  • Fine-Tune Tones without Changing the Image
    To fine-tune the tones in specific parts of a Photoshop image without permanently changing it, use the Dodge tool and the Burn tool on a new layer that is in Overlay mode and filled with 50 percent gray, which is neutral (invisible) in Overlay mode. Create this new layer via the Layers palette's pop-up menu, or Option- (Alt-) click on the New Layer icon at the bottom of the palette to open the New Layer dialog box. - Linnea Dayton and Jack Davis
  • Correct RGB Colors with Dodge and Burn
    A quick way to correct the color in one area of an image is to use Dodge and Burn. The Dodge and Burn tools lighten or darken a given area. Applying them to the grayscale values of an individual color channel changes that color in a local area. Select the desired channel from the Channels palette in Photoshop and set the visibility icon to the entire image composite so that you can view the whole image as you edit. Now select the Dodge and Burn tool and paint the image. Using the Dodge tool, paint in the Red channel to add red, the Green channel to add green, and the Blue channel to add blue. With the Burn tool selected, paint in the Red channel to add cyan, the green channel to add magenta, and the Blue channel to add yellow. - Daniel Giordan
  • Apply a Better Emboss
    Photoshop's Emboss filter sucks the color right out of images and only suggests the effect it promises. The best way to emboss in Photoshop is to emboss each channel separately, creating the effect interactively as you go. This works best with RGB and CMYK images, although other formats also work. Open the Channels palette and click on the Red channel (assuming you're working in RGB), which highlights to show that it's active. Now click on the visibility icon next to the RGB composite, which displays all the channels while letting you edit only the Red channel (middle), Select Filter, Stylize, Emboss, and rotate the Angle directional control until the emboss angle complements the angles in the image itself. Set the Height according to the overall resolution of the image: set low-resolution images between 2 and 4 pixels, high-res images between 3 and 7. Repeat these steps for the Green and Blue channels, modifying the Angle and Amount values to describe the various details in the image. - Daniel Giordan
  • Preview Adjustment Layer Changes
    It's easy to preview changes made via a Photoshop adjustment layer - such as changing an image's hue and saturation levels - to see how they affect areas of an image in real time. Simply select an area of the image, create the adjustment layer, and use the Move tool to drag the selection around. It may also help to use Photoshop's drag-out guides to divide your image into sections, such as quadrants. Make your adjustment-layer change to one quadrant, and move the selection around by quadrant, snapping to guides as you go. - Anita Dennis

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