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- Graver Help File: HOWTODO.DAT
-
-
- QUICK START GUIDE _______________________________________________
-
- 1) Load a BMP file to be converted from the File Open dialog
- box, or paste an image from the Windows clipboard using the
- Edit Paste menu command.
-
- 2) Click the RIGHT mouse button on an image area you wish to
- engrave. The Options dialog box will appear with the key
- color of your selected engraving areas shown. Click "OK" to
- accept the selected color and the default options.
-
- 3) Double-click the LEFT mouse button anywhere on the image
- to begin pixel conversion. Conversion will take a moment or
- two, depending on the size of your image and engraving areas.
-
- 4) When conversion is complete, a gray scale image will appear.
- Save the image with the File Save As dialog box, or Copy it
- to the clipboard.
-
- 5) Use your favorite BMP-to-GIF utility to generate a GIF file
- for use as a height field or bump map.
-
- That's all, except for a few helpful hints...
-
-
- INPUT IMAGE HINTS _______________________________________________
-
- Graver will accept and process any Windows BMP file up to the
- size and resolution of your full screen. For best quality, use
- the highest resolution you can with the Smoothing option on.
- Smoothing can be turned off for applications where roughness is
- desirable, such as in simulating tool marks on wood.
-
- Both 16-color and 256-color BMPs work as input files. However,
- since Graver needs the system palette, 256-color images will be
- displayed in shades of gray rather than in the original colors.
- This has no effect on image processing.
-
- The entire input image must be displayed on the screen during
- processing, so if you move Graver's window or cover the input
- image with another application's window, image conversion may be
- incomplete.
-
- Selecting a key color defines the regions of the input image to
- be engraved. All areas containing the key color you select will
- be converted to shades of gray representing depth. Input image
- pixels that are not in the engraved areas are converted to a
- single shade of gray whose value depends on the Concave/Convex
- Option setting.
-
- The Concave option is the mode for normal engraving where
- pixels in engraved areas grow darker (lower) toward the center.
- The Convex option is the reverse with engraved areas lightest
- at the center.
-
- Graver assigns a gray shade to each engraved pixel in proportion
- to its distance from the nearest edge of the engraved area, as
- defined by the the nearest pixel whose color is not the selected
- key color. To simulate the engraving style commonly found in
- stonecutting, Graver explores a square search region centered on
- each pixel to be engraved. The search algorithm uses information
- from prior searches to speed calculations.
-
- Engraving areas up to 50 x 50 pixels can be processed with
- Smoothing set to On, while areas up to 450 x 450 pixels can be
- handled with Smoothing set to Off. Any contiguous area larger
- than these limits will be clipped by assigning a single floor or
- ceiling gray value to pixels in the central part of the engraved
- area.
-
- The Edit Undo command can be used to restore display of the input
- image after processing so you can experiment with several option
- settings.
-
-
- OUTPUT IMAGE HINTS ______________________________________________
-
- At the completion of processing, a preview display of the output
- image appears. This display is useful for viewing the results of
- the conversion process, but some images and option settings will
- produce display contrast that is too low to be viewed directly.
- This is more often the case when Smoothing is off.
-
- The File Save As and Edit Copy commands are active when an out-
- put picture is visible. Undo can toggle between output and input
- pictures until you load a new image or start another conversion.
-
- Graver uses a special palette of 256 gray shades corresponding
- to 256 palette index values. To avoid Windows system palette
- conflicts, only the palette index values 10 to 235 are used in
- image conversions. The conversion options affect palette index
- values as follows:
-
- 1) When Concave is selected, the palette index of non-engraved
- areas is set to 235. Engraved area pixels are assigned
- decreasing values until the minimum index 10 is reached.
-
- 2) When Convex is selected, the palette index of non-engraved
- areas is set to 10. Engraved area pixels are assigned
- increasing values until the maximum index 235 is reached.
-
- 3) When Smoothing is on, the palette index steps 9 units for each
- unit of engraved area depth change. This allows averaging of
- 3x3 pixel regions to smooth the surface of engraved areas.
-
- 4) When Smoothing is off, the palette index steps 1 unit for each
- unit of depth change. This allows larger areas to be engraved
- without depth clipping.
-
- Windows file conversion utilities such as Paint Shop Pro nicely
- handle the translation of output files to GIF format without
- disturbing the palette.
-
-
- POV-RAY RENDERING HINTS _________________________________________
-
- When rendering height fields:
-
- 1) Smoothing by Graver exaggerates depth (the y-dimension). Try
- scaling to restore normal engraving proportions. Scale values
- of .1 to .3 seem to work well.
-
- 2) Even with smoothing by Graver, some height fields will have
- noticeable jaggies. POV-Ray's own 'smooth' keyword helps,
- though sometimes at the cost of fine details. Rendering with
- anti-aliasing is often the best solution.
-
- 3) Intersection operations between, say, a box and a height
- field allow you to use different textures for the flat surface
- and the engraving. See HELLO.POV for an example of gold
- lettering on stone.
-
- When rendering bump maps:
-
- 1) Bump maps are a good way to simulate engraving on a variety
- of solid objects. Unfortunately, the simulation is imperfect
- because the illusion of concave vs. convex varies with
- lighting angle and surface orientation. Experiment with
- Graver's Concave and Convex options to find the bump map
- that works best in your situation.
-
- 2) The 'interpolate 2' keyword works well with bump maps to
- reduce jaggies.
-
- 3) Large bump size values may be needed to create contrast with
- bump maps created by Graver. Try bump size values around 100
- for bump maps created with Smoothing Off, and values around
- 10 for those created with Smoothing On.
- _________________________________________________________________
-
- Richard LeVitt (c)1994
-
-