A novel image encryption approach based on a new 2D chaotic map and consisting of left map and right map utilizing image segmentation was proposed. The chaotic encryption of image is realized by processing image stretch-and-fold. Firstly

a square image was divided into two isosceles triangles along the diagonal

utilizing the difference of the pixel numbers of two adjacent columns of the triangles

each pixel in a column was inserted to the next adjacent column. Then

the original image could be stretched to a line. Finally

the line was folded over to a new square image whose size was the same as the original image. The process was invertible

so that the positions of image pixels could be used in image encryption. Taking the numbers of the left map and the right map as the keys

the algorithm of the map was formulated

the method of key generation was designed and the security of the proposed image encryption was analyzed. The simulation results show that the proposed encryption approach is valid. When the key is 64 bits

the whole key space size is 1.84×10

19

and the speed of encryption is 3 Mb/s. The image encryption has several advantages such as rapid speeds

high security and without message loss and it is easy for hardware/software realization.