Tactile images having coefficient of friction differences
A method for forming a tactile printed image on a receiver medium to convey information to a visually-impaired person from image data having an array image pixels with binary pixel values. The tactile printed image by depositing tactile marking material onto the receiver medium, wherein no tactile marking material is deposited onto portions of the receiver medium corresponding to image pixels having a first state, and tactile marking material is deposited onto portions of the receiver medium corresponding to image pixels having the second state. The receiver medium has a first coefficient of friction, and the portions of the tactile printed image having deposited tactile marking material are raised by at least 20 microns relative to the surface of the receiver medium and have a second coefficient of friction which differs from the first coefficient of friction by at least 0.06.
1. A method for forming a tactile printed image on a receiver medium to convey information to a visually-impaired person, comprising:
receiving tactile image data having an array of image pixels with tactile pixel values, the tactile image data defining a pattern of tactile features; and
forming the tactile printed image by depositing tactile marking material onto the receiver medium to provide the pattern of tactile features, wherein no tactile marking material is deposited onto portions of the receiver medium where the corresponding tactile pixel values indicate that no tactile features are to be formed, and wherein tactile marking material is deposited onto portions of the receiver medium where the corresponding tactile pixel values indicate that tactile features are to be formed;
wherein the receiver medium has a first coefficient of friction and the formed tactile features corresponding to the portions of the tactile printed image having deposited tactile marking material have a second coefficient of friction which differs from the first coefficient of friction by at least 0.20, and wherein the formed tactile features corresponding to the portions of the tactile printed image having deposited tactile marking material are raised by at least 20 microns relative to the surface of the receiver medium.
2. The method of claim 1 wherein the receiver medium has a lower coefficient of friction than the portions of the tactile printed image having deposited tactile marking material.
3. The method of claim 1 wherein the receiver medium has a higher coefficient of friction than the portions of the tactile printed image having deposited tactile marking material.
4. The method of claim 1 wherein the tactile marking material is substantially colorless so that the tactile printed image has an optical density of no more than 0.2.
5. The method of claim 1 wherein the tactile marking material includes a visible colorant so that the tactile printed image has an optical density is more than 0.2.
6. The method of claim 1 wherein the tactile marking material is deposited using an electrographic printing process.
7. The method of claim 1 wherein the tactile marking material is deposited using an inkjet printing process.
8. The method of claim 1 wherein the tactile marking material is deposited using a printing press.
9. The method of claim 1 wherein the tactile image data includes representations of one or more Braille characters.
10. The method of claim 1 wherein the tactile image data includes one or more image regions containing texture patterns.
11. The method of claim 1 wherein the tactile pixel values are binary pixel values having either a first state indicating that no tactile feature is to be formed or a second state indicating that a tactile feature is to be formed.
12. The method of claim 1 further including depositing one or more colored marking materials onto the receiver medium to form a color printed image in registration with the tactile printed image.
13. The method of claim 12 wherein the one or more colored marking materials include a cyan marking material, a magenta marking material, a yellow marking material or a black marking material.
14. A method for forming a tactile printed image on a receiver medium to convey information to a visually-impaired person, comprising:
receiving tactile image data having an array of image pixels with tactile pixel values, the tactile image data defining a pattern of tactile features; and
forming the tactile printed image by depositing tactile marking material onto the receiver medium, wherein no tactile marking material is deposited onto portions of the receiver medium where the corresponding tactile pixel values indicate that no tactile features are to be formed, and wherein tactile marking material is deposited onto portions of the receiver medium where the corresponding tactile pixel values indicate that tactile features are to be formed;
wherein the receiver medium has a first coefficient of friction and the portions of the tactile printed image having deposited tactile marking material have a second coefficient of friction which differs from the first coefficient of friction by at least 0.06, and wherein the portions of the tactile printed image having deposited tactile marking material are raised by at least 20 microns relative to the surface of the receiver medium;
wherein the deposited tactile marking material includes an additive that alters the coefficient of friction of the portions of the tactile printed image having the deposited tactile marking material relative to portions of a printed image having a deposited marking material with an identical formulation except that it does not include the additive.
15. The method of claim 14 wherein the additive is an abrasive material that increases the coefficient of friction of the portions of the tactile printed image having the deposited tactile marking material.
16. The method of claim 14 wherein the additive is a material that decreases the coefficient of friction of the portions of the tactile printed image having the deposited tactile marking material by providing a reduced surface energy.