I am trying to understand whether or not the web allow for viewing of progressive JPEG or not.
Assume we have a server where (see progressive jpegs):
$ identify /var/www/test.jpg
/var/www/test.jpg JPEG 2048x1080 2048x1080+0+0 8-bit DirectClass 129KB 0.020u 0:00.019
$ identify -verbose /var/www/test.jpg | grep Inter
now if we place the following HTML document:
$ cat /var/www/test.html
<p><img src="test.jpg" width="256" height="128"></p>
I am trying to understand whether or not (according to img element
), a user agent is required to download the whole
image, while rendering region is only
Or on the contrary a User Agent
, is allowed to take into account the rendering region:
, and therefore deduce it can only process a portion of the progressive
JPEG. Knowing that there is no point in having the full resolution since it will not add any details to the image (well technically a quality layer should impact even at low resolution, this is just for simplification).
Typically, I'd like to know within an application such as google maps, if a User Agent
can abort (suspend?) retrieval of currently displayed images, since User decide to zoom in some more based only on partial result from decompressing a progressive
JPEG (the whole JPEG is not yet on User side).