[jira] [Commented] (PDFBOX-1893) Refactor color spaces

["Andreas Lehmkühler (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PDFBOX-1893?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13894556#comment-13894556 ] 

Andreas Lehmkühler commented on PDFBOX-1893:
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Sounds reasonable and like a lot work.  ++1

Do you need a separate branch for this or do you want to use the trunk?

> Refactor color spaces
> ---------------------
>
>                 Key: PDFBOX-1893
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-1893
>             Project: PDFBox
>          Issue Type: Improvement
>          Components: PDModel, Utilities
>    Affects Versions: 2.0.0
>            Reporter: John Hewson
>            Assignee: John Hewson
>              Labels: color
>
> I'm currently working on this, so I wanted to open an issue to let everyone know.
> Color spaces need to be refactored in 2.0.0. Tilman noticed slowness in PDFBOX-1851 due to using ICC profiles and calling ColorSpace#toRGB for every pixel. For example, the file from PDFBOX-1851 went from rendering in 4 seconds to taking over 60 seconds.
> The solution is to use ColorConvertOp to convert an entire BufferedImage in one go, taking advantage of AWT's native color management module. Color conversions done this way are almost instantaneous, even for large images.
> The current design of color spaces within PDFBox depends upon conversions being done on a per-pixel basis, so a significant refactoring is needed in order to convert images using ColorConvertOp without having to resort to per-pixel calls in cases such as a Separation color space which uses a CMYK alternate color space via a tint-transform.
> The color space handling code is also tightly coupled to image handling. The various classes which read images each have their own color handling code which rely on per-pixel conversions. For this reason any color space refactoring must also included a significant refactoring of image handling code. This is an opportunity to refactor all color handling so that it is encapsulated within the color space classes, allowing downstream users to call toRGB(float[]) or toRGB(BufferedImage) and not need to worry about tint transforms and the like.



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