U.S. GEOLOGICAL SURVEY OPEN FILE REPORT 94-255 The Southern Lake Michigan Coastal Erosion Study CD-ROM By C.F. Polloni1, C.L. Brown2, D.W. Folger1, D.S. Foster1, and A.L. Brill3 Display software by Russell A. Ambroziak4 Documentation by Christine A. Cook4 1U.S. Geological Survey, Woods Hole, MA 02543 2U.S. Forest Service, Jacksonville, OR 97530 3Duke University, Durham, NC 27708 4U.S. Geological Survey, Reston, VA 22092 How to Use VIEWLBL VIEWLBL is a simple image viewer which uses ASCII label files to describe the binary image data files. The heart of the program is the label file, which is patterned after the Jet Propulsion Laboratory's (JPL's) 'IMDISP' ASCII label file. For program VIEWLBL, each image must contain its own separate label file. The simplest label file possible is a file of type '.lbl' containing the rows, columns, and image data file name. The following is an example of a simple '.lbl' file: (Please note: the examples contained within this document are for demonstration purposes only; the example '.lbl' files are not found on the OF94-255 CD-ROM. The '.lbl' files contained on the disc are patterned after the following examples and can be viewed with the DOS 'type' command.) IMAGE_LINES = 2057 LINE_SAMPLES = 1435 IMAGE_POINTER = PD356001.dat This will tell VIEWLBL to view the file 'PD356001.dat'. This '.lbl' file tells VIEWLBL that the image has 2057 lines and that each line contains 1435 pixels (picture elements). The image is assumed to be a gray-scale image with no color palette file. Each pixel will be one byte in size and there is no header in the image data file. There are a number of varieties to the above '.lbl' file, some of which appear on the OF94-255 disc. In order for VIEWLBL to function properly, the label, palette, and binary data files for the image should be located in the same directory. After typing 'viewlbl' at the DOS prompt, you will see a list of available '.lbl' files appear on the right side of the screen along with the following instructions: Use up and down arrow keys, PgUp or PgDn, or type the filename to position highlighted cursor. Hit 'Enter' to select the file or 'Esc' to leave this menu. Move the highlight bar over the image you wish to view, and hit or the left mouse button. You will then see the image displayed. Next, you will see a box appear in the upper right corner of the screen. This is the zoom box and can be manipulated with the above instructions. If you wish to zoom, hit ; if you do not wish to zoom, hit . Note: the mouse is inactive while in the zoom function. You will then see the following list of options at the top of the screen: System Zoom Analyze Plot Quit ------ ---- ------- ---- ---- color pixel info boundary targa file histogram labels .grf hide menu shade caption smooth rescale The following describes the functions: System ------ color The following functions alter the color of the image. change +/-,789,123: This allows you to change the color image as a whole. '+' increases the intensity and '-' decreases it. The number pad controls the hues. It is operated as follows: Red Green Blue --- ----- ---- 7 8 9 increases the hue value 1 2 3 decreases the hue value stretch RGB: If the color image does not use the full range of intensity in its color palette, you can stretch the colors. The option will have no effect on gray-tone images. There is no change in the hues or saturations of the colors. Only intensities are changed. reset: This will set the palette back to the original. change one color: If you wish one color on your image to be different, this function allows you to change that one color without changing any of the other colors. save new table: After you have altered the image colors, you can save the new palette information in place of the old information. It is a good idea to save a copy of the old palette file first before using this option. To save the old palette to a backup file, you must exit from VIEWLBL. exit color: This allows you to exit the color functions and returns you to the main SYSTEM menu. targa file: This allows you to output a 32-bit targa file of the image you are working with. hide menu: This will hide the menu. Hit or the right mouse button to see the menu again. Zoom ---- If the image is too large to fit on the screen, a subsampled image is displayed. This function allows a selected area of the sampled image to be viewed at full resolution. If the full- resolution image will fit on the screen, then this option is inoperative. A box appears on the image which represents the size and shape of a full-resolution (every pixel) sample of the image. The box can be moved 16 pixels at a time in any direction by using the arrow keys. To change the distance the box moves each time, use '+' and '-' keys to double and halve this value, respectively. The size (not the shape) of this box can be changed by using 'l' for larger and 's' for smaller. Hit to select a portion of the image or to exit without changing the display. Note, if the zoom box is made to be smaller than full-resolution, the box will change color. Beware of zooming in too far and thus causing replication of pixels to occur. Analyze ------- pixel info: This puts a cursor in the middle of the screen which can be moved to get pixel information. The cursor is moved with the arrow or number pad ('Num Lock' = off), and the amount of movement is con- trolled with '+' and '-'. The display at the bottom will change with available information but it will look something like this: x=256 y=416 84 r: 57 g: 31 b: 26 3520 5120 lat = 47.76468 lon = -126.63266 Not all images will have all of the above information. Some will only give x and y locations. In this example, the cursor on the screen is at pixel (256,416) which is pixel (3520,5120) in the image file. The value of the pixel on the screen is 84, while the values of the red, green, and blue pixels used to make the color image are 57, 31 and 26, respectively. These RGB values come directly from the files used to make the composite image and are not scaled in any way. histogram: This does a histogram of the screen data by data number (dn). The first choice is a box that asks where you want the graph. Use the following to position the histogram box: (l)arger (s)maller (H)igher (S)horter (W)ider (N)arrower '+' move more '-' move less Do not cover data with this box as it will be destroyed (on the screen only, not in the file.) When you are satisfied with the position of the histogram box, hit . After is hit, any information existing under the box will be blanked out. Next, a smaller box appears on the screen. This box is also operated by the commands above. After you have sized this box, hit ; the histogram of information contained within this box is then graphed in the area determined by the first box placement. To end this function, hit . shade: Makes a shaded-relief of the image with the light source to the right. This function asks for the contrast value (between 1 and 20). Trial and error will determine which is best; start with a contrast of 10 and work from there. smooth: Does a 3x3 average of the pixels. Use this before 'Shade'. rescale: This rescales the image to fit on the screen. Plot ---- boundary plot: If a vector section exists within the image .LBL file, this function allows you to plot those vectors. After you have called this function, a menu will appear on the right side of the screen with the vector sets listed. Move the highlight bar over the linework you want and hit . You will see the vectors plotted over the image. After they have finished plotting, the menu of vector sets will return. Either plot more linework, or exit this function to return to the main menu. labels .grf: This will plot point information found within a '.grf' file. caption: If a caption section exists within your image '.lbl' file, this option allows you to plot the caption. The caption will automat- ically plot on the subsampled image, but if you have zoomed into a section of the image, then the caption will not automatically plot; you have to call it up. After you have selected the caption function, you will see the caption plot in the lower right corner of the screen. Quit ---- This will return you to the list of all '.lbl' files. If you hit a couple of times, you will return to the DOS prompt.