Insert a tactile image
The tactile image insertion window allows you to choose some useful parameters for converting from a normal to a tactile image. This window is indispensable for a correct transformation of the images.
This input window appears after you choose a file with an image, or after you scan an image from the scanner.
The surface of the window is largely occupied by a box, which shows the preview of the tactile graph. In addition, a status bar shows density and fragmentation values similar to those described in the main tactile graphics window. To update the panel and the status bar, click on the Apply button.
This position is useful for choosing from which point in the touch graph the image should start. The position is expressed at a point, given by the X and Y coordinates. The point is always at the top left, so the image will always extend to the right and down. For example, to have the image printed from the top left of the sheet, the start point will be at the X 0 and Y 0 coordinates.
This size is useful for choosing the width and height of the touch image. Because of the small size of the touch area, compared to the resolution of a normal image, the points in a touch image will almost always be a reduction of the actual points in the source image.
The dimension shall be expressed in width and height. There is also a box for maintaining the aspect ratio of the image. If this box is activated, changing one of the dimensions will always be reflected on the other to maintain the proportions. If this box is checked, the width and height will be independent fields.
Horizontal and vertical reversals are useful boxes when you want to flip the image in one or both directions.
The box to invert the colors of the image is useful when you want to make the colors of the image in negative. The negative inverts the colors of the image, light with dark, dark with light. If the image is too dark, using some filters it is useful to put the image in negative to reduce the density. An example can be given by night pictures, where sky or other parts are black.
When converting to touch, isolated individual points may appear, i.e. not close to other tactile points. The box for removing isolated dots is used to remove them and make the image less jagged.
The image can be rotated 90°, 180° and 270°. The rotation is different from the inversion of the points, because the image is not flipped specularly, but is precisely rotated. The degrees of rotation are always clockwise.
Brightness is used to brighten or darken the colors of an image. The value in this box is always a percentage, positive or negative. A negative percentage darkens the points, a positive percentage lightens them.
The box with the color reduction type is an indispensable field for creating good tactile images. Pictures usually have a high amount of color. A tactile image, on the other hand, is usually made up of only two colours, the expression of raised and flat surfaces. Dark colors produce raised dots, light ones lower dots. Color reduction is essential to detect which points on the image should be raised or lowered.
Color reduction has several filters, which are used to convert the colors of the source image into tactile points. Visitors can preview the touch image that will be produced by using the Apply button and observing the touch image that will appear in a large pane. Visually impaired people can use the status bar, which contains the density and fragmentation values of the touch image. It is inevitable that visually impaired people, in order to produce good quality tactile charts, should always check the final result by printing the tactile chart. Usually, before you get a good result, you will need to print the tactile chart several times, until you find the most satisfying one.
These are the filters available:
- Grey tones
- Simple black and white
- Black and white dithering
- Pencil drawing
- Pen Drawing
- Edge Detector
Each filter has its own specific settings, which appear when you select. The characteristics of each filter will be dealt with separately in the subchapters of this page.
The Apply button is indispensable for simulating the tactile image, according to the chosen parameters. Almost in real time, the side panel will show the touch image and the status bar will show the updated density and fragmentation values. Usually this button can also be clicked by pressing Alt+P.
After setting the image parameters, you can click on the OK button and the image will be inserted into the tactile graph. Then you will return to the main window of tactile graphics.