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Modify and manage Raster Images

May 20, 2011

       Controls the properties such as displaying and clipping boundary of raster images. You can view and manipulate attached raster image and change its saving path in Image Manager.

Show and Hide Raster Image Boundaries

       Controls whether to display image boundary in current view using IMAGEFRAME command,. Raster image can be displayed without frame. Usually users select image entity by clicking image frame. Setting IMAGEFRAME to Off prevents you from accidentally selecting an image.

       Once hide the image frame, the image can't be selected by SELECT command, keep the clipped image displayed within specified frame.

     All the attached images update as soon as the visibility of raster image frame is set to display or hide.

To turn image frames on or off for all images

  1. Choose Modify > Object > Image > Frame.

  2. Do one of the following to toggle frames off and on:

  • Type on to display and print frames for all images in a drawing.

  • Type off to hide all frames on the screen and during printing.

Reference toolbar\

Command line IMAGEFRAME


Clip Raster Images

       You can get the desired part of the image displayed through imageclip, and also improve the redraw speed so as to define the display and plot area of the image.

       Two types of clipping boundary are provided as rectangle composed by lines and polyline. The vertex within an image boundary even if self-intersected vertex should be specified when you define new boundaries. Here rectangle boundary is the default pattern of clipping boundary. Only one clipping boundary is assigned for each image instance, but multiple instances of the same image can be assigned with different boundaries.

      The clipped image can be displayed within clipping boundary, and also displayed inside its original boundary.

       You can remove the clipping boundary of an image and use the original frame of the image to display the clipped image instead. But the boundary of the image to be clipped must be visible.


To clip an image in the shape of a rectangle

  1. Choose Modify > Clip > Image.

  2. Select the edge of the image you want to clip.

  3. If prompted, type new to create a new clipping boundary.

  4. Choose Rectangle.

  5. Define the first corner of the clipping rectangle.

  6. Define the second corner of the clipping rectangle. The selected image is clipped so that only the interior of the rectangle is visible.

Reference toolbar\

Command line IMAGECLIP

To clip an image in the shape of a polygon

  1. Choose Modify > Clip > Image.

  2. Select the edge of the image you want to clip.

  3. If prompted, type new to create a new clipping boundary.

  4. Choose Polygon.

  5. Select the points for the polygon, and then press Enter when the polygon is complete.The selected image is clipped so only the interior of the polygon is visible.

Reference toolbar \

Command line IMAGECLIP

To turn clipping on or off for an image

  1. Choose Modify > Clip > Image.

  2. Select the edge of the image for which you want to turn clipping on or off.

  3. Type on or off.

Reference toolbar \

Command line IMAGECLIP

To remove clipping from an image

  1. Choose Modify > Clip > Image.

  2. Select the edge of the image for which you want to remove clipping.

  3. Type delete.

Reference toolbar \

Command line IMAGECLIP

Change Raster Image Brightness, Contrast, and Fade

      Use IMAGEADJUST to adjust displaying result and lightness, contrast and fade that are related to the display and plot effect when plotting drawings, IMAGEADJUST does not affect the original raster image as well as other instances of the image.

      You can set lightness and contrast to better preview images of lower quality.

      To change the fade of the image, geometric lines will be clearly viewed and add watermark effects when plotting the image.

      If you attach a bitonal image into the drawing, you can't set the lightness, contrast, and fade. Bitonal images are displayed as background color of current screen, and plotted as white.

Modify Color and Transparency for Bitonal Raster Images

       Bitonal raster Image contain a foreground color and a background color, so that the current color settings determine the foreground color of the bitonal image as attached into the drawing. Although the lightness, contrast, and fade are not adjustable for bitonal images, you can modify the foreground color of the image and control its transparency from the Properties palette.

NOTE Bitonal images and their boundaries are always the same color.

View Raster Image Information

       The raster images already attached to the drawing are displayed in list or tree view in Image manager. You can click Details button to view the relevant information of the raster image.

List View

       System defaults to use List view for displaying the name, status(load, unload or not found), size, type, last save date and time as well as saving path of the image file.

       Click on the column title to rank the images. If the original file of the inserted image is missing, the image status is displayed as "Not found". Images that are unloaded or not found in the image manager will not be displayed in the drawing.

Tree View

Sorts the raster images in tree view and display the hierarchy of the images nested in xrefs and blocks.

View Image FileDetails

     Click DETAIL button to preview a selected image and view image file details, including image name, saved path, active path (where the image is found), file creation date, file size, file type, color, color depth, image size (pixel width and height, resolution and default size).

Assign Descriptive Names to Raster Images

      You can change the name of an image by double click the file listed on the image manager. You can assign the image name different from the its file name, the image is attached into the drawing without extension name.

      To rename an image, any name within 255 characters including letters, numbers, spaces and all the special characters Microsoft® Windows® or ZWCAD can be used.

       If two raster images of the same name originated from different paths are attached to the drawing, system automatically distinguish them by adding numbers after the image name.

Change File Paths of Raster Images

       The raster images already attached to the drawing are displayed in Image manager and its saving path is displayed in "Image found at" option at the bottom of Image manager. Where the saving path is the virtual path for searching the image file.

     If the original image attached to the drawing is not exist in the saving path or any defined searching path, the status of the image is displayed as Not found and the "Image found at" box is blank.

     The Drawing File Search Path can be set or modified at the Files tab in Options dialog box, so that the raster image of the drawing file can be located. If the raster image having been attached to the drawing is moved to another folder, its relative path or absolute path information will be removed from its file name (for example, to turn \images\tree.tga or c:\my project\images\tree.tga into tree.tga), and search for the path defined at Drawing File Search Path the Files tab in Options dialog box.

     If the specified extension name of the drawing is not found at the saving path, system searches for all the image file extension names.

     The path of the image can be removed, or directly edit the path in Image found at box and then select Save path to specify its relative path. This may be different from the path in Image found at box. Changing the path in Image Manager does not affect settings in "Drawing File Search Path".

To change the path for a raster image

  1. Choose Insert > Image Manage.

  2. Select the desired file.

  3. Click the Browse button.

  4. Select the file with its new name or in its new location, and then click Open.

  5. Click Save Path.

Insert toolbar\

Command line IMAGE

Load and Unload Raster Images

     If excessive raster images exist in current drawing, you can unload the undesired images so as to raise the capability of your computer. Once the raster image is unloaded from the drawing, it'll be displayed as image boundary disabled of plotting. And the links of the image does not change after unloaded. If too much images attached to the drawing cause memory lacking in process of opening the drawing, system automatically unload part of image files.

      Once unloaded, you can reload the images already unloaded from the drawing. If you close the unloaded drawing after saving it, this drawing file is only available by reloading it next time you open the drawing.

To unload and reload a raster image

  1. Choose Insert > Image Manage.

  2. Select the file you want to unload or reload.

  3. Do one of the following:

  • To unload the image so only its outer edge displays, click Unload.

  • To reload the image so its contents display and print, click Reload.

Insert toolbar \

Command line IMAGE

Improve the Display Speed of Raster Images

      The display quality of images may affect its properties directly, the higher the quality, the longer it displayed. Any changes to the image display speed will be updated immediately rather than redraw the drawing. System plots the drawing at its high quality.

      You can adjust the display speed by setting the raster image quality. The image quality is sorted into high and draft levels, If the quality is set to draft, the image will be displayed with some granular materials, however with faster display speed.

      If the attached raster image uses true color ( 24 or 32 bit each pixel), you can adjust relevant options in Display tab on Options dialog box so as to improve the image quality. System takes a long time to redraw the drawing when it displayed at high quality. To improve the capability, it's suggested to reduce the color number set at the display option.

      In purpose of improve the redraw speed, you can hide the undesired images in current drawing operations through Show image option on the Properties palette. The hidden image will be neither displayed on the screen nor plotted, only displayed as a boundary. To hide an image, you may ignore the UCS of current viewport.

To change the quality of all images in a drawing

  1. Choose Modify > Object > Image > Quality.

  2. Do one of the following:

  • Type high to use high quality images.

  • Type draft to use draft quality images, which require smaller amounts of system resources.

Reference toolbar \


Use Tiled Images

      Tiled image is a series of small parts of large images. Loading tiled images is faster than loading those untiled images due to the tiled images redraws its modified parts to save time in loading images. ZWCAD supports TIFF for tiled image file format which is also available for bitonal gray( 1 bit per pixel) and index color ( 8 bit per pixel), true color( 24 or 32 bit per pixel).

      Tiled TIFF images can be saved by image scanners. But you must limit the pixel within the range 64 × 64 to 512 × 512 when tiling images. You can get programs that support other tiled file formats from third party program developer.

Suppress Highlighting When Selecting Images

      Generally, the image will be highlighted once selected. Set the "Highlight raster image frame only" option in "Display" tab on "Options" dialog box to turn on or off the highlight mode for the specified raster image. Besides, system variable IMAGEHLT is also available for controlling the highlight mode of the image frame. Set the IMAGEHLT to 0, only highlight the frame of the raster image. You should turn off highlight mode for the whole drawing so as to improve the capabilities of your computer.

Change the Temporary Swap File Location of Raster Images

      Temporary swap file is useful when you want to reduce the memory space that image file occupies. Windows Temp folder is the default saving path provided by system, you can also specify new Temp file search path in Files tab on Options dialog box.

Commands Reference

IMAGE: Manages images

IMAGEATTACH: Attaches a new image to the current drawing

IMAGEFRAME: Controls whether image frames are displayed or hidden from view

IMAGECLIP: Creates new clipping boundaries for an image object

PROPERTIES: Controls properties of existing objects

IMAGEADJUST: Controls the image display of the brightness, contrast, and fade values of images

TRANSPARENCY: Controls whether background pixels in an image are transparent or opaque

OPTIONS: Customizes the ZWCAD settings

IMAGEQUALITY: Controls the display quality of images

System Variables Reference

PROJECTNAME: Assigns a project name to the current drawing

IMAGEHLT: Controls whether the entire raster image or only the raster image frame is highlighted 

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