The display image should be free of geometric nonlinearity distortion.
Additional Information: For different rows or columns of text, the difference of length should be a maximum 1.0 percent of the intended length of that column or row. For a more fine-grained determination of linearity, the horizontal displacement of a symbol position relative to the symbol positions directly above and below that symbol position, should be a maximum of 5.0 percent of the symbol box width. The vertical displacement of a symbol position, relative to the symbol positions to the right and left of the symbol position, should be a maximum of 5.0 percent of that symbol box height. Lines and columns should be parallel and orthogonal one to the other within the limits of the linearity requirement. This may be expressed as:
0.04 (Shorter edge/Longer edge) >= Diag1/Diag2—1.
The variation in size of a specific symbol anywhere on the display should be a maximum of 10 percent, regardless of its location within the image area. This is expressed as follows:
2(h2 - h1) / (h2 + h1) <= 0.1, and 2(w2 - w1)/(w2 + w1) < 0.1,
where h is the height of the symbol and w is the width of the symbol. When all the character positions on the screen are filled with “H”s or “M”s of the same character set, h1 is the height of the smallest character, h2 is the height of the largest character, w1 is the width of the smallest character, and w2 is the width of the largest character. 9 5908, 9241-303
© ISO. This material is excerpted from ISO 9241-303: 2011 with the permission of ANSI on behalf of ISO. All rights reserved.