3D AutoCAD 2004/2005: One Step at a Time

24.2 Working with Raster Images: The Image Manager

For working with raster images, AutoCAD provides an Image Manager very similar to the Xref Manager we used in our last lesson. Access it with the Image command.

Notice the similarities (Figure 24.2a). In fact, all of the buttons that you find in the Image Manager work the same way they work in the Xref Manager – with a couple of notable exceptions.

Figure 24.2a

First, there's no Open button. If you wish to open the graphic for editing, you'll have to do it in its own program.

Then, if you'll notice the fifth button down on the right side of the Image Manager, you'll see that the button reads Details…. (This button reads Bind… in the Xref Manager.) The significance of this is really quite important: You can reference an image file from, but you can't bind an image file to an AutoCAD drawing. The Details… button, however, provides some useful information about the highlighted file (see Figure 24.2b).

Figure 24.2b

Notice that the Image File Details dialog box provides information about the size, location, and type of file providing the image.

24.2.1 Attaching, Detaching, Loading, and Unloading Image Files

As with the Xref Manager, you can use the Image Manager to attach, detach, load, or unload image files. Notice the similarity between the Image dialog box (Figure 24.2.1a) and the External Reference dialog box we discussed in our last lesson (Figure 23.1.1c). They're almost identical and the function of each button/frame is the same.

Figure 24.2.1a

Again, there are a couple of notable exceptions.

• The Scale frame of the Image dialog box has only one text box. The reason for this is simple: While you could scale a reference drawing file along the XYZ axes, a raster image has no XY or Z-axis along which to scale. Therefore, AutoCAD restricts us to a uniform scale for raster images.

• There is a Retain Path check box in the Image dialog box. Unlike the Xref Manager, you can't save the path "relative to" the path to your primary drawing. With images, you either save the path or you don't.

Let's reference some images into a file.

Do This: 24.2.1.1 Working with Images

1. Open the cutting table24.dwg file in the C:\Steps\Lesson24 folder. The drawing looks like Figure 24.2.1.1a.

   Figure 24.2.1.1a

2. Thaw the Marker layer.

3. Enter the following command sequence:

   Command: imageframe

   Enter image frame setting [ON/OFF] <ON>: off

   [We'll discuss image framing after this exercise, but for now, it's best to have it turned off.]

4. Follow these steps.

   TOOLS	COMMAND SEQUENCE	STEPS
   Image Button	Command: im	1. Open the Image Manager by typing image or im at the command prompt. Alternately, you can pick the Image button on the Reference toolbar.
   		2. AutoCAD presents the Image Manager (Figure 24.2a). We'll attach a logo in the title block, so pick the Attach… button.
   		3. AutoCAD presents a Windows Select… File dialog box. Select the logo.gif file in the :\Steps\Lesson24 folder, as shown. Pick the Open button to continue.
   		4. AutoCAD presents the Image dialog box. Be sure there is a check in the Specify on-screen check box in the Insertion point frame. Clear the check boxes in the other frames. Enter 1.65 into the Scale frame's text box. Pick the OK button to continue.
   		5. Insert the image at the node in the title block (just left of the words "AutoCAD 2004"). The title block looks like Figure 24.2.1.1.5a. (There may be a frame around the logo – ignore it for now. We'll fix the problem of the graphic covering the drawing in a later exercise.)
   	Figure 24.2.1.1.5a
   Image Attach Button	Command: iat	6. Now let's use the ImageAttach command to insert a photograph of the cutting table. Enter imageattach or iat at the command prompt. Alternately, you can pick the Image Attach button on the Reference toolbar.
   		7. Repeat Step 3, but select the cutting table.jpg file.
   		8. This time enter a scale of .75, and insert the image at the node in the middle of the screen (~6,5). Pick the OK button to continue. Your drawing looks like Figure 24.2.1.1.8a.
   	Figure 24.2.1.1.8a
   	Command: qsave	9. Save the drawing but don't exit.

   Note

   Images attach on the current layer. You can freeze them, turn them off, lock them, and so forth just like any other object.

Over the course of this exercise, did you try to adjust either of the images we referenced? Did you notice that you couldn't select either one? If not, try to erase one of them now.

Unlike Xrefs, which allow you to use OSNAPs and other modifying tools, images have no vector geometry to select. But AutoCAD doesn't leave you with something you can't modify. It provides a system variable – called ImageFrame – that reveals a selectable frame around the image. The command prompts:

Command: imageframe

Enter image frame setting [ON/OFF] <OFF>:

When OFF, images in the drawing are not selectable; that is, you can't modify them. When ON, AutoCAD shows a frame around the image. You can select this frame to move, scale, or otherwise modify the image.

In our next exercise, we'll use the frame to adjust our view of the photograph.

24.2.2 Clipping Image Files

Clipping an image is no different from clipping an Xref. The command sequence is identical:

Command: imageclip (or icl)

Select image to clip: [select the image you wish to clip]

Enter image clipping option [ON/OFF/ Delete/New boundary] <New>: [tell AutoCAD what you want to do]

Enter clipping type [Polygonal/Rectangular]

<Rectangular>: [tell AutoCAD what type of clipping boundary you wish to use]

Specify first corner point: Specify opposite corner point: [identify the corners of the rectangle or the vertices of the polygon]

The ImageClip command automatically activates the ImageFrame system variable so that you can select an image.

Let's clip our photograph.

Do This: 24.2.2.1 Clipping Images

1. Be sure you're still in the cutting table24.dwg file in the C:\Steps\Lesson24 folder. If not, please open it now.

2. Follow these steps.

   TOOLS	COMMAND SEQUENCE	STEPS
   Image Clip Button	Command: icl	1. Enter the ImageClip command by typing imageclip or icl at the command prompt. Alternately, you can pick the Image Clip button on the Reference toolbar.
   	Select image to clip:	2. (Notice that AutoCAD activates the ImageFrame system variable.) Select the frame around the cutting table photograph.
   	Enter image clipping option [ON/OFF/Delete/New boundary] <New>: [enter] Enter clipping type [Polygonal/Rectangular] <Rectangular>: [enter]	3. Hit enter twice to accept the New and Rectangular boundary defaults.
   	Specify first corner point: Specify opposite corner point:	4. Place a rectangle around the image of the cutting table as shown in Figure 24.2.2.1.4a. AutoCAD clips the photograph. The results look like Figure 24.2.2.1.4b.
   	Figure 24.2.2.1.4a	Figure 24.2.2.1.4b
   	Command: qsave	5. Save the drawing but don't exit.

We could do the same thing for the logo, but I want to show you another tool we can use there. Let's continue.

24.2.3 Working with Image Files

AutoCAD provides four tools for use with graphic images that aren't available (nor would they be useful) for Xrefs. These include: ImageAdjust, ImageQuality, Transparency, and DrawOrder.

• The ImageAdjust command calls the Image Adjust dialog box (Figure 24.2.3a). Here you can adjust the brightness, contrast, or fading effect (how well the image blends with the background color of the drawing) of the image. The dynamic preview image helps you see the results of your modifications before you accept them with the OK button.

  Figure 24.2.3a

  Like ImageClip, ImageAdjust automatically activates the ImageFrame system variable.

• ImageQuality is a system variable that affects only the display of your graphic images. It presents the following prompt:

  Command: imagequality

  Enter image quality setting [High/ Draft] <High>:

  High quality presents the best possible image in the display, but it may cause some delay in the initial display or redraw/regen time. Draft quality isn't quite as pretty, but it allows for much faster displays. AutoCAD will always use High quality when plotting despite this setting.

• The Transparency command works only on certain types of graphics that have a transparency property. Our logo has been created with a transparent background, so we'll see this property in our next exercise.

  You can set transparency on a per-image basis.

• [We'll discuss DrawOrder after the next exercise.]

Let's experiment with these commands before looking at our last tool.

Do This: 24.2.3.1 Image Quality and Transparency

1. Be sure you're still in the cutting table24.dwg file in the C:\Steps\Lesson24 folder. If not, please open it now.

2. Follow these steps.

   TOOLS	COMMAND SEQUENCE	STEPS
   	Command: z	1. We'll begin by adjusting the cutting table photograph. Zoom in a bit closer to it.
   Image Adjust Button	Command: iad	2. Enter the ImageAdjust command by typing imageadjust or lad at the command prompt. Alternately, you can pick the Image Adjust button on the Reference toolbar.
   	Select image(s): Select image(s): [enter]	3. Notice that ImageAdjust activates the ImageFrame sysvar. Select the frame around the photograph, and then hit enter to continue.
   		4. AutoCAD presents the Image Adjust dialog box (Figure 24.2.3a). Work with the three settings until you're pleased with the preview image. (Use the Reset button in the lower left corner if you need to return to the original settings.) Pick the OK button when you're satisfied.
   	Command: imagequality	5. Now we'll set the ImageQuality to speed our display time. Enter the command by typing it at the command prompt. Alternately, you can pick the Image Quality button on the Reference toolbar.
   		6. Tell AutoCAD to use a Draft quality. Notice the change in the photograph (compare Figures 24.2.3.1.6a and 24.2.3.1.6b). Remember that the ImageQuality setting affects only the display.
   	Figure 24.2.3.1.6a:	Figure 24.2.3.1.6b
   		7. Adjust your display to view the logo.
   Image Transparency Button	Command: transparency	8. We'll use the Transparency command to see the title block through the image. Enter the command at the command prompt or pick the Image Transparency button on the Reference toolbar.
   	Select image(s): Select image(s): [enter]	9. Notice again that the image frame becomes visible. Select the frame around the logo. Hit enter to continue.
   	Enter transparency mode [ON/OFF] <OFF>: on	10. Turn ON the transparency. Notice the difference (Figures 24.2.3.1.10a and 4.2.3.1.10b).
   	Figure 24.2.3.1.10a: Transparency is OFF	Figure 24.2.3.1.10b: Transparency is ON
   	Command: z	11. Zoom all.
   	Command: qsave	12. Add the Product text, freeze the Marker layer, and save the drawing. It now looks like Figure 24.2.3.1.12a.
   	Figure 24.2.3.1.12a

   • Our last image modification tool is called DrawOrder. By default, AutoCAD displays the last object drawn or inserted atop (or over) previously drawn objects. This may cause certain objects to "hide" behind other objects. DrawOrder allows you to control the order in which objects are displayed. In other words, use DrawOrder to control which object appears on top. It presents the following sequence:

     Command: draworder (or dr)

     Select objects: [select an object to modify]

     Select objects: [select more objects or hit enter to confirm the set]

     Enter object ordering option [Above object/Under object/Front/Back] <Back>: tell AutoCAD how to reposition the image/object]

The options are best explained in an exercise, so let's begin.

Do This: 24.2.3.2 Controlling Drawing Order

1. Open the DispOrd.dwg file in the C:\Steps\Lesson24 folder. The drawing looks like Figure 24.2.3.2a. (The drawing has two polylines and an image.).

   Figure 24.2.3.2a

2. Follow these steps.

   TOOLS	COMMAND SEQUENCE	STEPS
   Draw Order Button	Command: dr	1. Enter the DrawOrder command by typing draworder or dr at the command prompt. Alternately, you can pick the Draw Order button on the Modify II toolbar.
   	Select objects: Select objects: [enter]	2. Select the red horizontal polyline.
   	Enter object ordering option [Above object/Under object/Front/Back] <Back>: f	3. Move it to the front. Notice the change in the display (Figure 24.2.3.2.3a).
   	Figure 24.2.3.2.3a

I created this file to give you a chance to play with the various options of the DrawOrder command. Take a few minutes to experiment with each of the options.