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https://issues.apache.org/jira/browse/IMAGING-162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14302875#comment-14302875
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Myroslav Golub edited comment on IMAGING-162 at 2/3/15 7:25 AM:
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[~mgmechanics], here's the link: http://www.fileformat.info/format/bmp/egff.htm
Following are quotes from the document:
{quote}
Width and Height are the width and height of the image in pixels, respectively.
If Height is a positive number, then the image is a "bottom-up" bitmap with the
origin in the lower-left corner. If Height is a negative number, then the image
is a "top-down" bitmap with the origin in the upper-left corner.
{quote}
{quote}
Scan lines are stored from the bottom up if the value of the Height field in
the bitmap header is a positive value; they are stored from the top down if the
Height field value is negative.
{quote}
Wikipedia states this as well:
http://en.wikipedia.org/wiki/BMP_file_format#Pixel_array_.28bitmap_data.29
{quote}
Unless BITMAPCOREHEADER is used, uncompressed Windows bitmaps also can be
stored from the top to bottom, when the Image Height value is negative.
{quote}
Microsoft's own documentation:
https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376%28v=vs.85%29.aspx
{quote}
If biHeight is positive, the bitmap is a bottom-up DIB and its origin is the
lower-left corner. If biHeight is negative, the bitmap is a top-down DIB and
its origin is the upper-left corner.
{quote}
was (Author: mgolub):
[~mgmechanics], here's the link: http://www.fileformat.info/format/bmp/egff.htm
Following are quotes from the document:
{quote}
Width and Height are the width and height of the image in pixels, respectively.
If Height is a positive number, then the image is a "bottom-up" bitmap with the
origin in the lower-left corner. If Height is a negative number, then the image
is a "top-down" bitmap with the origin in the upper-left corner.
{quote}
{quote}
Scan lines are stored from the bottom up if the value of the Height field in
the bitmap header is a positive value; they are stored from the top down if the
Height field value is negative.
{quote}
Wikipedia states this as well:
http://en.wikipedia.org/wiki/BMP_file_format#Pixel_array_.28bitmap_data.29
{quote}
Unless BITMAPCOREHEADER is used, uncompressed Windows bitmaps also can be
stored from the top to bottom, when the Image Height value is negative.
{quote}
> BMP files with negative bitmap height are not suported
> ------------------------------------------------------
>
> 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
> Fix For: Patch Needed
>
>
> 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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