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From "Myroslav Golub (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (IMAGING-162) BMP files with negative bitmap height are not supported
Date Sun, 22 Feb 2015 15:22:11 GMT

    [ https://issues.apache.org/jira/browse/IMAGING-162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14332214#comment-14332214
] 

Myroslav Golub commented on IMAGING-162:
----------------------------------------

The format specifcation says the following:
http://www.fileformat.info/format/bmp/egff.htm
{quote}
The bottom-up configuration is the most common, because scan lines stored from the top down
cannot be compressed. 
{quote}

Microsoft's documentation says:
https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376%28v=vs.85%29.aspx
{quote}
If biHeight is negative, indicating a top-down DIB, biCompression must be either BI_RGB or
BI_BITFIELDS. Top-down DIBs cannot be compressed.
{quote}

> BMP files with negative bitmap height are not supported
> -------------------------------------------------------
>
>                 Key: IMAGING-162
>                 URL: https://issues.apache.org/jira/browse/IMAGING-162
>             Project: Commons Imaging
>          Issue Type: Bug
>          Components: Format: BMP
>    Affects Versions: 1.0
>            Reporter: Myroslav Golub
>              Labels: github
>             Fix For: Review Patch
>
>         Attachments: monochrome-negative-height.bmp
>
>
> The BMP format allows for negative values of the height field in the header. This means
that the image lines are stored top-down, not bottom-up as usual (i. e. the first pixel in
the pixel array would be in the top left corner of the image, not in the bottom left as usual).
However, when a negative-height bitmap is passed, the BmpImageParser attempts to create an
array of negative length, and a NegativeArraySizeException ensues.



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