please give me correct way of movemenent. where can i get useful info? 
what i want is: - 

there is the form with parameters and 2 buttons: Search, Reset.

i want to implement logic - input some params and click search button - GridView as result is shown below.

examples, articles would be helpful.Thanks!
['https://Stackoverflow.com/questions/13724271', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/1450372/']
Are the devices all running the same version of the OS? Another possibility (beyond colorspaces, which someone already mentioned) is that the JPG decoding libraries may be subtly different. As JPEG is a lossy image format, it's not inconceivable that different decoders would produce resulting bitmaps that were not bit-equal. It's seems reasonable to posit that, given the heavy use of images in iOS UI, that the JPG decoder is something that would be undergoing constant tuning for maximum performance. 

I'd even believe it conceivable that between the same OS version running on different models of device (i.e. different processors), the results could be not bit-equal if there were multiple versions of the JPG decoder, each heavily optimized for a specific CPU, although that would not explain the difference between 2 devices of the same model, with the same OS.

You might try to re-run the experiment with an image in a lossless format.

It also may be worth pointing out that providing your own backing memory for a CGBitmapContext, but not making special allowances for word alignment is likely to lead to poor performance. For instance, you have:

```
NSUInteger imageBytesPerRow = bytesPerPixel * imageWidth;

```

If imageBytesPerRow is not a multiple of the CPU's native word length, you're going to get sub-optimal performance.
I assume the "device grey" color space varies by device. Try with a device independent color space.