Photo engraving using GridPhoto

Creation of milling data in GridPhoto.

GridPhoto is a convenient solution for 2D photo engraving. Grey scale images are converted from programs using a few Mouse clicks into high quality milling data for almost all 3 or 4 axis machine tools. In GridPhoto, grey scale images are processed and converted into dotted or linear milling data. The photos should be available as grey scale images with 256 colours (exception .jpg). The imported images can be edited, scaled, filtered, mirrored and very rapidly converted into milling data.

With milling there results a gridded image which resembles a photo, for example in a daily newspaper The light/dark variations (grey scales) in the photo are created through dots or lines with appropriate intensity or density.

Using Milling data graphics you can monitor the calculated milling data and, as required, repeat the calculation with modified settings as often as you wish.

GridPhoto has available various grid, dither and hatching processes for the creation of optimum milling data. In the grid process grey scales are created through dots with varying diameter and the same separations (3D milling data). The dither process creates grey scales through dots with the same diameter and variable separations (2Dmilling data). With the hatching process the grey scales are represented through 2D hatching lines in adjustable directions and separations.

Help on the functions can be obtained with the activated navigator using , in the menu also using [?] and clicking-on the function.

Import photo.

Import a grey scale image and adjust dimensions (measurements). The program imports Bitmap files (256 Grey scales, 8Bitgrey scales, 1Byte/Pixel) in the following formats:

Before calculation of the milling path a photo should be processed into a photostyler (e.g. Corel PHOTO-PAINT) and saved as grey scale image (8Bit/Pixel – not in colour, exception .jpg). Images in the .jpg – format can also be saved as colour images (24Bit). On import these are converted into grey scale images.

Gridded photos (e.g. from periodicals) have a very rough surface and should as far as possible be avoided or reworked in a suitable photostyler. Gridded images can also be improved using approximate fine/strong.

Height – width ratio (Input in mm): 

Modify frame.

Edit the relief limits (clip or expand relief).

Scaling.

Adjust a relief in size and resolution.

Filter.

Revise/smooth the photo. Suitable filters are, for example, approximate.

Mirror + rotate.

In the case that it has still not taken place the image can be rotated or mirrored in all axes. Mirror complete image in X, Y, Z and rotate by +/-90°.

Line gridding.

Using line gridding  grey scale images are milled using a conical tool in 3D lines. The tool, depending on image brightness sinks to different depths in the material and thus creates the photo in the workpiece. Light areas of the image result in small milling depths and, through the tool cone, small line widths. Dark areas of the image, on the other hand, result in large milling depths and wide lines.

With import of the photo the image is converted into a relief. The measurements X/Y are the dimensions of the photo (reliefs). These ca be adjusted using ‘scaling’. The milling depth is determined by the relief depth (input/modification, for example using scaling . dimension Z).

For the engraving of photos no large milling depths are necessary, usually a few 0.1 mm suffice. The normal procedure is the engraving of the image and subsequent covering (filling) of the cutter track using colour. With the employment of multi-layer material the thickness of the upper milling layer must be noted (set the safety height (Off) higher and incise slightly deeper).

Display in upper window.

Inputs.

Tool #:	Selection of a suitable milling tool. For milling, conical tools (with cone angle (CAn) >0°, e.g. 20..30°)are always to be employed. The cutter tip should be selected as small as possible (CuT <0.1 mm). For small cutter tips always pay attention to sufficient rpm.
Line separation [10..500%]:	The line separation is related to the tool radius with max. milling depth (100%). The milling path separation is determined by the line separation. A larger line separation results in a larger milling line separation and an image with a lighter effect. Recommended settings for photo engraving are 100% .. 300%. Reliefs (e.g. Lithophane for transmitted light) can be milled using the program. For this a tool with larger tip radius or spherical radius and smaller line separation (ca. 10..50%) is to be selected. With line gridding only a tool offset of the cutter tip is calculated. We therefore recommend the relief module or the program eMillRelief for correct relief production.
Angle [-90..+90°]:	Setting of the angle of the milling lines. 0° produces horizontal lines.
Procedures:	Milling method selection: Hatching: Simple lines without turnaround. Cross hatching: Simple lines without turnaround + 90° rotated crossings. Hatching meander: Lines in zigzag order. Cross hatching meander: Lines in zigzag order + 90° rotated crossings. Rectangle: Rectangles concentrically ordered. Circle: Circles concentrically ordered. Spiral: Elliptical spiral. Radial lines: Simple radial lines without turnaround. Radial lines meander: Radial lines in zigzag order. Spiral > rectangle: Elliptical spiral go over to rectangle form.
Layer depth [mm]:	Dependent on the Max. Milling Depth Z the image can be milled in one or more layers. If the layer depth is exceeded, the program creates several milling layers.
Contrast [-0.5..+0.5]:	With values >0 the image is higher-contrast (light and dark grey scales are reinforced). With values <0 are milled with less contrast.
Inverse [Y/N]:	YES: The brightness levels are inverted. Light areas are milled dark, dark areas are milled light.

Lines 100%

Cross-hatching 150%

Gridding.

Using gridding the grey scales in the image are created by dots of various diameter and the same separations. The variable dot diameters are created using a conical tool, which is sunk (inserted) appropriately deep into the material. Small dot diameters are achieved through small insertion, large dot diameters through strong insertion (3D milling data). Conical tools and a 3D machine tool are demanded for the grid process.

Display in upper window.

Inputs.

Tool tip radius [mm]:	Smaller dot separations and a greater total number of dots can be achieved using a small tip radius. The tip radius should be selected as small as possible (finest grid dot).
Tool angle[°]:	Conical tools are required for gridding. Convenient tool angles lie at 40..49°. Smaller tool angles increase the milling depth.
Safety height (SH) [mm]:	Safety clearance of the cutter tip to the surface of the material for withdrawn movements. The smaller the safety height is chosen the more dots can be milled at the same time.
Processes:	Milling processes for the image. Vertical: Each dot is milled vertically from the safety height into the material (long movements). Inclined from Mat.: The dots are milled into the material inclined along the tool angle. Up to the next dot an inclined movement takes place up to the material surface (short 3D movements). Lines: The individual milling depths are connected together by lines so that milled lines of different depth and thus different stroke widths result (short 3D movements). Inclined from  SH: The dots are milled inclined along the tool angle into the material. Up to the next dot an inclined movement up to the safety height takes place (long 3D movements).
Dot separation [mm]:	Separation of the grid points. The dot separation must be selected at least  4 x Tool tip radius, otherwise no contrast is possible within the image. The greater the ratio  Dot separation/ Tool tip radius is selected, the more contrast is possible in the milled image.
Density value:	A density value < 0 results in a lighter image after the engraving.

Example for dot grid.

Example for line grid.

Dithering.

New process from Ver. 7.022

The dither process creates the grey scales in the image through dots with the same diameter but variable separations (2D milling data). Cylindrical or conical tools can be employed for the dither process. A 2D (2.5D) machine tool suffices for the milling processing.

The dither milling data can, in a wide range, be matched to the job definition. An image milled using the dither process is effective from a minimum viewing separation. A sufficiently large image should also be milled. The program offers 3 milling processes:  Dithering 9p, Dithering 16p and Dithering 25p. Dithering 25p should be used for large area images only, Dithering 9p is suitable for rather smaller images.

To test a  suitable milling image select Settings (see below) and Start. You can repeat the calculation using changed settings as often as you like. For a rapid graphic set the Milling data aspect to Milling point

Through the relatively large-area dither dots the dimensions of the graphic cannot be adhered to exactly. The deviation of the milled image is visible in the graphic.

Display in the upper window.

Inputs.

Comparison of the dither processes. From left to right 9p, 16p and 25p. Above spread 0, below spread 0,5.

Same image as above but double dimensions and brightness + contrast respectively 0.1. Setting s. image.  Milling data view setting Relief view.

Hatching.

Convert grey scale image into hatched image. For this the grey scale number is reduced and the individual level replaced by hatching so that a gridded image results. For an as high as possible contrast result a photo should be processed in a photostyler beforehand. Here, disruptive elements should be removed and a stronger contrast selected. For the hatching a tool must be determined whose tip is to be selected as fine as possible (Cutter tip [CuT] 0.05..0.1mm). The hatching separations are determined automatically using the cutter tips, the grey level and the following settings.
    

Tool input for hatching.

For the creation of milling data complete tool information is required. The tool data are entered in the tool list. The tool list can be reached with Tool Input.

Milling data view

This setting of the milling data view is employed if milling data has been calculated using gridding, dithering or hatching. The black indicated form of view is set. The forms of view in blue can be selected.

Milling data graphics.

Drawing of the milled image in plan view with filled cutter trace (cutter simulation).

Milling data > Layer. (Only for CAD/CAM complete system)

Take over the milling data in a graphic layer.

Milling data export.

Following calculation, the milling paths can be exported in various formats.

Navigator.

In the Navigator  the most important program functions are summarised in the correct processing order. The Navigator leads you through the processing. Processing takes place from top to bottom. You can select the function marked in black. If a function is not to be selected then, using next you switch to the next operation. Using back you switch to the previous function.

Using GridPhoto grey scale images are converted into milling data for 3 or 4 axis machine tools. The photo must be available in a readable pixel format (BMP, PCX, gif, jpg) with 256 grey scales. Photos in other formats must be converted into the required format beforehand using a standard photostyler (e.g. Corel Photo Paint). In the photostyler, delete unwanted areas of the image and cut the image into the desired dimensions. Convert colour images and images with other tones into greyscale images with 256 gradations (grey scales (8 Bit)).Alternatively, you can also save the image in .jpg format with 24 Bit colour depth.

Import photo.

To work with GridPhoto the employment of the Navigator is recommended (it is active with first start). You open the image file using Import Photo.

The program immediately shows you the input to the image scaling. Here you set the dimension of the milling data. For the example dimensions of X = 50 mm, Y = 54.4 mm are desired. For this, first put proportional to YES and change the dimension X to 50 mm. After clicking-on the next number all values are changed proportionally (the image format is retained).

Filter.

The image is present in an unsatisfactory quality. The quality can be improved using the installed filters. Using approximate the image is smoothed and somewhat improved.

Mirror + rotate.

As required the image can here be rotated or mirrored.

Calculate milling data.

For this case the image is to be gridded using 3D dots. for this the function Gridding is selected (settings see picture).

Export milling data.

Before export, the milling paths should be viewed regularly using Milling data graphics. For these milling data a 3D milling machine with controlled X, Y and Z axes is required. Exported are the milling data using Export milling data andthe selection of the desired export filter.

In Export filter selection, select for example DIN/ISO and the export filter WinPC-NC / PC-NC. Note: For PC-NC the core image format for arcs (ABSOLUTE/relative) must be set the same in both programs (under Parameter).

The approach position, with -9999.99, can be switched off for X and Y. In this case the working off starts with the 1st work position.

Finished!