Progressively compressed images would choke many image applications though they can be viewed by most recent browsers. The questions is: how can you tell a jpeg image you are viewing is indeed a progressive image? Answer: ImageMagick. The identify utility can report a lot of detailed information about a jpeg image.
Run the command "identify -verbose something.jpeg". Check the Interlace property. Any value other than none would indicate that you are checking a progressive image. If you can even get any attribute of a jpeg image, it must be a progressive compression image as well.
That's all it takes.
C:\Program Files\ImageMagick-6.5.6-Q16>identify -verbose C:\share\Images\Graysca
le\HP-5301.jpg
Image: C:\share\Images\Grayscale\HP-5301.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Class: DirectClass
Geometry: 1728x2160+0+0
Resolution: 100x100
Print size: 17.28x21.6
Units: Undefined
Type: Grayscale
Base type: Grayscale
Endianess: Undefined
Colorspace: RGB
Depth: 8-bit
Channel depth:
gray: 8-bit
Channel statistics:
gray:
min: 0 (0)
max: 255 (1)
mean: 139.215 (0.545943)
standard deviation: 26.0522 (0.102165)
kurtosis: 12.7584
skewness: -0.414397
Histogram:
7484: ( 0, 0, 0) #000000 black
...
57837: (255,255,255) #FFFFFF white
Rendering intent: Undefined
Interlace: JPEG
Background color: white
Border color: rgb(223,223,223)
Matte color: grey74
Transparent color: black
Page geometry: 1728x2160+0+0
Dispose: Undefined
Iterations: 0
Compression: JPEG
Orientation: Undefined
Properties:
date:create: 2008-09-02T16:00:05-07:00
date:modify: 2008-07-30T17:31:01-07:00
jpeg:colorspace: 2
jpeg:sampling-factor: 2x2,1x1,1x1
signature: 670f9b1b583ea5871c2717785c5d9f8e7d794bd5492b652bb5d792fe21f5665b
Profiles:
Profile-APP12: 15 bytes
Artifacts:
verbose: true
Tainted: False
Filesize: 194kb
Number pixels: 3.56mb
Pixels per second: 12.67mb
User time: 0.281u
Elapsed time: 0:01
Version: ImageMagick 6.5.6-1 2009-09-14 Q16 OpenMP http://www.imagemagick.org
C:\Program Files\ImageMagick-6.5.6-Q16>
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