[jira] [Comment Edited] (PDFBOX-6155) AT (Adaptive template pixels) -1 byte skipped

["Maruan Sahyoun (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PDFBOX-6155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18074016#comment-18074016 ] 

Maruan Sahyoun edited comment on PDFBOX-6155 at 4/16/26 2:41 PM:
-----------------------------------------------------------------

[~tilman] I changed GenericRefinementRegion.updateOverride() to 

{code}
        case 0:
            if (grAtX[0] != -1 || grAtY[0] != -1)
            {
                grAtOverride[0] = true;
                override = true;
            }

            if (grAtX[1] != -1 || grAtY[1] != -1)
            {
                grAtOverride[1] = true;
                override = true;
            }
            break;
{code}

as I think the {{&&}} was wrong here as if I'm not mistaken it's about the AT not being in it's default position. Now excluding {{bitmap-symbol-textrefine-customat.jbig2}} from the ignores 

{code}
            if (name.equals("bitmap-refine-template1-tpgron.jbig2") ||
                name.equals("bitmap-symbol-context-reuse.jbig2") ||
                name.equals("bitmap-symbol-symhuffrefine-textrefine.jbig2")) // ||
                // name.equals("bitmap-symbol-textrefine-customat.jbig2"))
            {
{code}

the tests still pass - WDYT?
 


was (Author: msahyoun):
[~tilman] I changed GenericRefinementRegion.updateOverride() to 

{code}
        case 0:
            if (grAtX[0] != -1 || grAtY[0] != -1)
            {
                grAtOverride[0] = true;
                override = true;
            }

            if (grAtX[1] != -1 || grAtY[1] != -1)
            {
                grAtOverride[1] = true;
                override = true;
            }
            break;
{code}

as I think the {{&&}} was wrong here. Now excluding {{bitmap-symbol-textrefine-customat.jbig2}} from the ignores 

{code}
            if (name.equals("bitmap-refine-template1-tpgron.jbig2") ||
                name.equals("bitmap-symbol-context-reuse.jbig2") ||
                name.equals("bitmap-symbol-symhuffrefine-textrefine.jbig2")) // ||
                // name.equals("bitmap-symbol-textrefine-customat.jbig2"))
            {
{code}

the tests still pass - WDYT?
 

> AT (Adaptive template pixels) -1 byte skipped
> ---------------------------------------------
>
>                 Key: PDFBOX-6155
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-6155
>             Project: PDFBox
>          Issue Type: Sub-task
>          Components: JBIG2
>    Affects Versions: 3.0.4 JBIG2
>            Reporter: Tilman Hausherr
>            Assignee: Tilman Hausherr
>            Priority: Major
>         Attachments: bitmap-symbol-textrefine-customat.pdf, bitmap-symbol-textrefine-negative-delta-width.pdf, bitmap-symbol-textrefine.pdf
>
>
> bitmap-symbol-textrefine-customat.pdf has a garbled shape, however bitmap-symbol-textrefine.pdf doesn't. The difference is that the problematic one has 4 AT bytes.
> [https://github.com/SerenityOS/serenity/blob/master/Tests/LibGfx/test-inputs/jbig2/json/bitmap-symbol-textrefine-customat.json]
> {code:json}
> "refinement_adaptive_template_pixels": [
>                     10,
>                     -1,
>                     4,
>                     15
>                 ],
> {code}
> After a lot of reading and searching and trying I was able to trace it to {{GenericRefinementRegion.updateOverride()}} which ignores AT bytes if they are -1. However the specification says no such thing:
> 6.3.5.3 Fixed templates and adaptive templates
> The AT pixel RA1 can be located anywhere in the field shown in Figure 7, not including the current pixel. The AT pixel
> RA2 can be located anywhere in the range (-128, -128) to (127, 127) in the reference bitmap.
> See also figure 7 earlier in the specification, which has (-1,-1) values.
> Just removing the two lines fixes the problem but ruins bitmap-symbol-textrefine-negative-delta-width.pdf, which has all -1 so I'll research that.



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