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I'm converting images to a MOV file, and had an interesting thing happen to me. I logged my bits per color component, bits per pixel, and bytes per row. Here's my code:
NSLog(@"Image width: %d, Height: %d", CGImageGetWidth(image), CGImageGetHeight(image));
NSLog(@"BPC: %d \ BPP: %d \ ByPR: %d", CGImageGetBitsPerComponent(image), CGImageGetBitsPerPixel(image), CGImageGetBytesPerRow(image));
Here's my output:
Image Width: 300, Height: 300 (everything's as expected) BPC: 8 (8 bits per color...so far so good) BPP: 32 (32 = 4 components ARGB * 8 bits per color...got it) ByPR:1216 (300 px per row * 4 bytes per pixel = 1200 bytes per row)
Why am I logged 1216 bytes per row, and not 1200? By the way, this isn't just a fluke. When I create a video based on those numbers for buffer sizes, it works. When I create it with 1200 bytes per row, I get some messed up aliasing effect.
Thoughts?!
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Each pixel typically consists of 8 bits (1 byte) for a Black and White (B&W) image or 24 bits (3 bytes) for a color image-- one byte each for Red, Green, and Blue.
Step 1: Multiply the detectors number of horizontal pixels by the number of vertical pixels to get the total number of pixels of the detector. Step 2: Multiply total number of pixels by the bit depth of the detector (16 bit, 14 bit etc.) to get the total number of bits of data.
Images are made of a grid of pixels aka “picture elements”. A pixel contains 8 bits (1 byte) if it is in BW (black and white). For colored images it uses a certain color scheme called RGB (Red, Green, Blue) represented as 1 byte each or 24 bits (3 bytes) per pixel.
As each RGB pixel has three sets of 8-bit binary numbers it therefore has 24 bits of computer information in total. Hence the term '24-bit colour'. And as 8 bits equals 1 byte, each RGB pixel therefore equals 3 bytes in file size.
The system likes images to be a multiple of 64 bytes per row, presumably for better performance due to cache line alignment. 1200 is not a multiple of 64, but 1216 is.
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