I have a picture of size 512 x 1024 and draw it as a texture with GL_TRIANGLE_STRIP. When I zoom it with glScalef(zoom, zoom, 1.0f) artifacts begin starting from zoom = 2.5
1) When zoom between 2.5 and 12 there is artifact on triangles border as shown in attached picture
2) When zoom greater 12 texture is rotated on 180 degrees
Can anybody help?
P.S. I didn't test on real device. Can it be emulator's bug?

Also I noticed that the problem occurs when size of picture on emulator screen is greater than size of real picture.

Added simple code that reproduces the problem. Can anybody test it on emulator and on real device and say results?