The pHYs chunk encodes the
absolute or relative dimensions of pixels. For example, an image scanned
at 600 dots per inch has pixels with known, absolute sizes--namely, one
six-hundredth of an inch in both x and y directions. Alternatively, an
image created on a 1280 × 1024 display will have nonsquare pixels, and
the relative dimensions of each pixel, also referred to as the aspect
ratio, may be stored so the image can be displayed as it was intended to
be seen.
The
component uses this information only when the image is draw using
DrawUsingPixelInformation procedure.
The name for this chunk is pHYs.
Components
> TChunkpHYs