Fixed typo.

 

From: Jayathirth D V 
Sent: Thursday, June 02, 2016 5:08 PM
To: Philip Race
Cc: Jim Graham; 2d-dev@openjdk.java.net
Subject: RE: Review Request for JDK-8152672 : Exception while getting second 
image properties for JPEG with embedded thumbnail

 

Hi Phil,

 

We have two kind of images with which we are able to reproduce the issue:

1)      sample.jpg present in JBS bug(We can't use this image because it is 
licensed ).

2)      JpegEmbedThumbnail.jpg taken using Prasanta's camera and used in webrev.

 

 

sample.jpg : 

 

If we do getNumImages() it will return 2. getNumImages() follows the same logic 
of skipping markers with length and registering SOI to get number of images.

sample.jpg has markers as follows :

SOI -> APP1 - > SOI -> EOI -> APP1 End -> EOI -> SOI -> EOI

 

I have dumped first image its SOI is first one in the above list and for second 
image it is third one in the list. getNumImages() counts first and third SOI 
for number of images. But in case of skipImage() we are getting inside APP1 
marker and considering its SOI.

 

JpegEmbedThumbnail.jpg :

 

If we do getNumImages() it will return 1.

JpegEmbedThumbnail.jpg has markers as follows :

SOI -> APP1 -> SOI -> EOI -> APP1 End -> APP2 -> SOI -> APP2 End -> APP2 -> EOI 
-> APP2 End -> EOI 

 

getNumImages() counts only first SOI for number of images. But in case of 
skipImage() we will are getting inside APP1 and APP2 markers also.

 

Thanks,

Jay

From: Phil Race 
Sent: Thursday, June 02, 2016 4:05 AM
To: Jayathirth D V
Cc: Jim Graham; HYPERLINK 
"mailto:2d-dev@openjdk.java.net"2d-dev@openjdk.java.net
Subject: Re: Review Request for JDK-8152672 : Exception while getting second 
image properties for JPEG with embedded thumbnail

 

I am bit doubtful about this. Are you sure we are correct in reporting two 
images to begin with ?
Thumbnails should not get counted ..


-phil.

On 06/01/2016 01:06 AM, Jayathirth D V wrote:

Updated bug title in JBS as it was misleading.

 

From: Jayathirth D V 
Sent: Wednesday, June 01, 2016 12:48 PM
To: Philip Race; Jim Graham
Cc: HYPERLINK "mailto:2d-dev@openjdk.java.net"2d-dev@openjdk.java.net
Subject: Review Request for JDK-8152672 : Exception getting thumbnail size for 
JPEG with embedded thumbnail

 

Hi,

 

Please review the following fix in JDK9:

 

Bug : https://bugs.openjdk.java.net/browse/JDK-8152672 

 

Webrev : HYPERLINK 
"http://cr.openjdk.java.net/%7Ejdv/8152672/webrev.00/"http://cr.openjdk.java.net/~jdv/8152672/webrev.00/
 

 

Issue : When we are trying to get properties related to second image in JPEG 
file we are getting IIOException mentioning that it is not a JPEG file.

 

Root cause : When we are skipping first image to reach second image header, we 
are just trying to find next available EOI marker. But if first image has 
embedded thumbnail in APP1 marker, we will reach to EOI of this thumbnail and 
not EOI of first image. So after we reach EOI of embedded thumbnail we try to 
access second image SOI marker which will fail.

 

Solution : We have to change the logic of how we skip to consecutive images in 
JPEG file. We know that application markers, comments or other markers can 
contain data same as SOI & EOI. Instead of just checking for EOI marker 
serially, we should read length of these markers and skip them.

 

Thanks,

Jay

 

 

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