COVERING OUR TRACKS October 2002
by John
Mantzefield
copyright 2002
While
I was searching the internet for images to edit and
composite into JPGs for the PMUG web site I noticed
some really nifty looking photos of electronics
equipment. It occurred to me that parts of these images
could be worked into a cover design for Mouse Tracks. I
was searching from the www.google.com/mac site where I
had the “Image” tab selected.
BASIC FUNCTIONALITY
Photoshop’s (Ver. 6.X) primary function is the compositing of painted and/or altered images. Two of it’s key features that makes this possible are it’s ability to layer one image over another, and then to adjust the transparency of these layers. Photoshop’s Layers Window displays the names of the layered images (or you can assign names) your working with and allows you to easily change the stacking order of these images. Their order is changed by clicking on any layer (in the name area - by default “Layer 1”, etc.) and dragging it up or down in the window - the change is instantly visible in the work space of your final image. The image that appear at the top of the Layers Window is visually the front layer on your monitor.
EXTRACTING
SELECTIONS
When images are composited it’s necessary to make many changes to their size, contrast and outlining or shading. One of the primary tool sets used to achieve this is the Selection Tools. By selecting a particular area of an image and deleting others you end up with isolated objects like the security monitor in the upper left corner of this months cover. One of the Selection Tools that some people find difficult to use is the Extract feature. The instructions that follow are rather detailed and may seem confusing at times, but stick with it and you’ll have a really nice tool at your disposal. This powerful tool is employed by selecting the layer to perform the Extract selection on and then opening the Image menu and choosing Extract (In PS-CS2 v9 it’s now in the FILTER menu). The full screen dialog box that appears looks pretty much like the image to the left. I have altered it’s appearance somewhat to make it more useful with this article.
The cover photo of the camcorder and it’s operator was shot indoors with a digital still camera (Nikon 990) - after the original JPG (2048 X 1536 @ 72pi) was Saved As a Photoshop file the background was removed using the Extract feature. When your image opens in the Extract window it looks just like it did in the work area where you see the final composited images. After outlining the areas you want to save (or extract) it looks like the part of the image to the right labeled “Initial Selection”. The green painted area labeled “Green Is Edge Highlighting” is that part of the image that is being defined as the perimeter of the area to be extracted.
Using the Edge Highlighter tool, which paints a transparent brush stroke (green by default), you simply paint a broad line around the area that you want to keep. To make it easier to paint around fine detail in your image just magnify the view by selecting the Zoom Tool (press OPTION key to Zoom out) and use the Hand Tool to move around the image as you highlight the edges. To see the tool names open Edit->Preference->General - in the Options area check “Show Tool Tips”... hold the mouse cursor over the tool icon for a moment and it's name will appear in a small text box.
TIPS AND TRICKS
Here’s a few tips to make this process a little easier. As you move your cursor over the various Extract tools you’ll see a brief description of it’s function in a text box along the bottom of the Extract window. Paint the edge highlights in rather short strokes, so if you accidentally paint in the wrong area you can quickly backtrack by pressing Com-Z (Undo last paint stoke). In the Tool Options area (see image above) you can change the paint brush size with the pull down size menu or by typing a number, OR with the tool selected press the Right or Left Bracket keys (to the right of the “P” key on your keyboard) repeatedly and the tool's size is automatically increased or decreased. Sometimes you need to zoom way in and change the brush to a very small size so that a detailed selection can be extracted.
BASIC FUNCTIONALITY
Photoshop’s (Ver. 6.X) primary function is the compositing of painted and/or altered images. Two of it’s key features that makes this possible are it’s ability to layer one image over another, and then to adjust the transparency of these layers. Photoshop’s Layers Window displays the names of the layered images (or you can assign names) your working with and allows you to easily change the stacking order of these images. Their order is changed by clicking on any layer (in the name area - by default “Layer 1”, etc.) and dragging it up or down in the window - the change is instantly visible in the work space of your final image. The image that appear at the top of the Layers Window is visually the front layer on your monitor.
When images are composited it’s necessary to make many changes to their size, contrast and outlining or shading. One of the primary tool sets used to achieve this is the Selection Tools. By selecting a particular area of an image and deleting others you end up with isolated objects like the security monitor in the upper left corner of this months cover. One of the Selection Tools that some people find difficult to use is the Extract feature. The instructions that follow are rather detailed and may seem confusing at times, but stick with it and you’ll have a really nice tool at your disposal. This powerful tool is employed by selecting the layer to perform the Extract selection on and then opening the Image menu and choosing Extract (In PS-CS2 v9 it’s now in the FILTER menu). The full screen dialog box that appears looks pretty much like the image to the left. I have altered it’s appearance somewhat to make it more useful with this article.
The cover photo of the camcorder and it’s operator was shot indoors with a digital still camera (Nikon 990) - after the original JPG (2048 X 1536 @ 72pi) was Saved As a Photoshop file the background was removed using the Extract feature. When your image opens in the Extract window it looks just like it did in the work area where you see the final composited images. After outlining the areas you want to save (or extract) it looks like the part of the image to the right labeled “Initial Selection”. The green painted area labeled “Green Is Edge Highlighting” is that part of the image that is being defined as the perimeter of the area to be extracted.
Using the Edge Highlighter tool, which paints a transparent brush stroke (green by default), you simply paint a broad line around the area that you want to keep. To make it easier to paint around fine detail in your image just magnify the view by selecting the Zoom Tool (press OPTION key to Zoom out) and use the Hand Tool to move around the image as you highlight the edges. To see the tool names open Edit->Preference->General - in the Options area check “Show Tool Tips”... hold the mouse cursor over the tool icon for a moment and it's name will appear in a small text box.
TIPS AND TRICKS
Here’s a few tips to make this process a little easier. As you move your cursor over the various Extract tools you’ll see a brief description of it’s function in a text box along the bottom of the Extract window. Paint the edge highlights in rather short strokes, so if you accidentally paint in the wrong area you can quickly backtrack by pressing Com-Z (Undo last paint stoke). In the Tool Options area (see image above) you can change the paint brush size with the pull down size menu or by typing a number, OR with the tool selected press the Right or Left Bracket keys (to the right of the “P” key on your keyboard) repeatedly and the tool's size is automatically increased or decreased. Sometimes you need to zoom way in and change the brush to a very small size so that a detailed selection can be extracted.
If
you need to paint an edge highlight along a straight
area in your image, click once at one end, then hold
the Shift key down before you click the next point -
the brush stroke will be drawn as a straight line.
(This line painting technique works in all paint
functions) If straight lines are being drawn where you
don’t want them this is occurring because your ending
one paint stroke, pressing Shift and clicking the next
point... you need to click a NEW single START POINT
(even if it’s over the end of the previously painted
area) to begin the new straight
stroke.
FILLING THE AREA
Once the Edge Highlighting is completed in the Extract window you will need to finalize this part of the process by selecting the Fill Tool and CLICK ONCE in that part of the image (inside or outside the Edge Highlight) that you want to KEEP - in the image above this is labeled “Blue Is Fill Area”. If the Filled area still isn’t correct, use the Eraser Tool to remove some of the Edge Highlight and re-Fill the area.
Once everything looks OK click the Preview button and you’ll see what I have labeled as “Preview of Area”. Even though this appears to be the final image alteration, there are still several repair options you can implement. To undo the whole thing and begin painting a new Edge Highlight, hold down the Option key in the Extract window and the Cancel button becomes a Reset button. If you want to make changes to just a few spots around the edges select the Cleanup Tool to erase small areas, or the Edge Touchup Tool to redefine the edge, that is, to sharpen it. Other settings can help too, like Smoothing (adjusts edge detail) and selecting other Masking and Cutout Colors. Also depending on the colors in your image you may need to change the Edge Highlight or Fill colors.
A WORD OF CAUTION
If you click anywhere on the image at this point with the Eraser or the Edge Highlighter tools the image will revert back to the point you were at just before you clicked the Preview button (in Preview->Show, select Original). While this is a valid technique to begin again, there are other ways to complete the project. Once you click the OK button and your back to the standard work space, try using the History Brush to replace edge detail or remove more of it with the Eraser Tool.
Once I have reached the Preview stage this is usually the last thing I’ll do with the Extract feature. While it does a good job of defining the major areas in a scene, it’s now time to zoom way in on the image (400 to 600% magnification) and hand paint out the final compositing imperfections. Usually really fine edge detail (like hair or feathers) can not be detected through an automated process like Extract without a mono-colored background (like Chromakey green or blue) behind the subject. I have read accounts of big budget special effect movie productions where dozens of digital artists were hired (equipped with Wacom tablets and high end paint programs) to laboriously paint out compositing imperfections on a frame by frame basis.
USING
CUSTOM BRUSH PRESETS
In the cover image you’ll notice that a couple of the larger background elements on the left side have raged or coarse edges. This was done by applying a Layer Mask to those images and painting out the right hand edges with a Custom Brush like you see outlined in the image to the right. To make a Custom brush paint a black brush strokes like the ones you see to the right. Use the Marquee tool to select the area around the new painted brush, then choose Edit>Define Brush Preset (in PS-CS2) and enter a name. This new brush will appear at bottom of the Brush palette. If the new Brush Preset doesn’t work out, Control click on the Brush icon in the Brush Preset menu and select either Rename or Delete. These cover elements (and others) had two Layer Styles applied to them. These are accessed at the bottom of the Layers palette from an icon that looks like a black disk with a white lightning bolt. For these elements I used a Drop Shadow and Outer Glow style.
FILLING THE AREA
Once the Edge Highlighting is completed in the Extract window you will need to finalize this part of the process by selecting the Fill Tool and CLICK ONCE in that part of the image (inside or outside the Edge Highlight) that you want to KEEP - in the image above this is labeled “Blue Is Fill Area”. If the Filled area still isn’t correct, use the Eraser Tool to remove some of the Edge Highlight and re-Fill the area.
Once everything looks OK click the Preview button and you’ll see what I have labeled as “Preview of Area”. Even though this appears to be the final image alteration, there are still several repair options you can implement. To undo the whole thing and begin painting a new Edge Highlight, hold down the Option key in the Extract window and the Cancel button becomes a Reset button. If you want to make changes to just a few spots around the edges select the Cleanup Tool to erase small areas, or the Edge Touchup Tool to redefine the edge, that is, to sharpen it. Other settings can help too, like Smoothing (adjusts edge detail) and selecting other Masking and Cutout Colors. Also depending on the colors in your image you may need to change the Edge Highlight or Fill colors.
A WORD OF CAUTION
If you click anywhere on the image at this point with the Eraser or the Edge Highlighter tools the image will revert back to the point you were at just before you clicked the Preview button (in Preview->Show, select Original). While this is a valid technique to begin again, there are other ways to complete the project. Once you click the OK button and your back to the standard work space, try using the History Brush to replace edge detail or remove more of it with the Eraser Tool.
Once I have reached the Preview stage this is usually the last thing I’ll do with the Extract feature. While it does a good job of defining the major areas in a scene, it’s now time to zoom way in on the image (400 to 600% magnification) and hand paint out the final compositing imperfections. Usually really fine edge detail (like hair or feathers) can not be detected through an automated process like Extract without a mono-colored background (like Chromakey green or blue) behind the subject. I have read accounts of big budget special effect movie productions where dozens of digital artists were hired (equipped with Wacom tablets and high end paint programs) to laboriously paint out compositing imperfections on a frame by frame basis.
In the cover image you’ll notice that a couple of the larger background elements on the left side have raged or coarse edges. This was done by applying a Layer Mask to those images and painting out the right hand edges with a Custom Brush like you see outlined in the image to the right. To make a Custom brush paint a black brush strokes like the ones you see to the right. Use the Marquee tool to select the area around the new painted brush, then choose Edit>Define Brush Preset (in PS-CS2) and enter a name. This new brush will appear at bottom of the Brush palette. If the new Brush Preset doesn’t work out, Control click on the Brush icon in the Brush Preset menu and select either Rename or Delete. These cover elements (and others) had two Layer Styles applied to them. These are accessed at the bottom of the Layers palette from an icon that looks like a black disk with a white lightning bolt. For these elements I used a Drop Shadow and Outer Glow style.
