[Libreoffice-bugs] [Bug 113068] New: In Slide Show, speckles (colored pixels) appear around text displayed on top of an image

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=113068

            Bug ID: 113068
           Summary: In Slide Show, speckles (colored pixels) appear around
                    text displayed on top of an image
           Product: LibreOffice
           Version: 5.3.6.1 release
          Hardware: x86 (IA32)
                OS: Windows (All)
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: Impress
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: davidjudysmith at gmail.com

Description:
If text overlays an image (photo), then in Slide Show the characters of text
may be surrounded by sprinkles of colored pixels.  These speckles fall mostly
along horizontal and vertical lines; I speculate that they may be related to
the edges of the jpeg blocks.

This problem exists in 5.3.6.1 and 5.4.2.2.  It does not exist in 5.2.6.2 and
5.2.2.2.  I have not tried any other versions.

I will attach a sample presentation file that shows the problem, along with a
couple of screen captures that illustrate what I see.

Variations:
* The speckles appear for all of the fonts that I have tried, and for normal,
bold, italic, and bold-italic versions of those fonts.
* Interestingly, the speckles do not appear for outline fonts.
* The appearance of the speckles, and their color, do not depend on the color
of the text characters.
* The speckles depend on the "darkness" of the image.  If the text is over a
white or nearly white area, there are no visible speckles.  They are
conspicuous over a cloudy blue sky.  If the background is very dark and with
much detail (like a forest scene), there may be speckles, but they won't be
obvious.

Steps to Reproduce:
1. On a new slide, insert an image.  I used a jpeg photo, slightly compressed
but still with high quality.  Enlarge the image if necessary to fill, or mostly
fill, the slide.
2. Draw a rectangle over an appropriate area of the image.  ("Appropriate area"
means not completely white, and not absolutely smooth and featureless, but
still light enough to see speckles.) Set the fill pattern of the rectangle to
None, so that the image underneath is completely visible.
3. Type some text into the rectangle.  Select all of the text and enlarge the
point size to something big -- maybe 80 or more.  If desired, change the font
or color.
4. Start the slide show.  In one of the affected versions, speckles should be
visible around the text characters.

Actual Results:  
See screen captures, attached.

Expected Results:
No speckles.


Reproducible: Always

User Profile Reset: No

Additional Info:


User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36
(KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36

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