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From Jay Chiu <jayc...@ureach.com>
Subject Re: Re: Problem with scaling png image file in svg
Date Sun, 15 Feb 2004 18:01:01 GMT

Chris,

I have successfylly solved the problem. I think it is a fop
bug.

I have just changed 2 lines of PDFGraphics2D.java:
line 289: and line 296
FROM: 
Dimension size = new Dimension(imageInfo.width * ratio,
imageInfo.height * 3);
and
g.fillRect(0, 0, imageInfo.width * ratio, imageInfo.height *
3);
TO:
Dimension size = new Dimension(imageInfo.width * ratio,
imageInfo.height);
and
g.fillRect(0, 0, imageInfo.width * ratio, imageInfo.height);
I think it is not necessary to enlarge the image 3 times. After
the change, the PDF image object forpng in svg is almost the
same as that directly in pdf file: 
external png image
6 0 obj
<</Type /XObject
/Subtype /Image
/Name /Im1
/Length 26341
/Width 500
/Height 400
/BitsPerComponent 8
/ColorSpace /DeviceRGB
/Filter [ /ASCII85Decode /FlateDecode ]
>>

svg png image
11 0 obj
<</Type /XObject
/Subtype /Image
/Name /Im2
/Length 26341
/Width 500
/Height 400
/BitsPerComponent 8
/ColorSpace /DeviceRGB
/Mask [255 255 255 255 255 255]
/Filter [ /ASCII85Decode /FlateDecode ]
>>

Another thing I found out is that JIMI support is not required
for png file in svg. So probably fop should be able suport png
file natively. 

Please have add my change change into your next release of FOP.

Thanks a lot.

Jay
  




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---- On Thu, 12 Feb 2004, Jay Chiu (jaychiu@ureach.com) wrote:

> Thanks Chris,
> 
> I feel the difference for external png file and SVG are, Fop
> uses JIMI to handle the external png file, while Batik loads
the
> png image into BufferedImageCachableRed object and fop
> PDFGraphics2D class handles png image in SVG. The
> org.apache.fop.svg.PDFGraphics2D class is equivalent to
> org.apache.fop.image.JimiImage for fop external png file.
Both
> external png file and png in SVG are processed by
> PDFXObject.output method in the end. With the same png file
of
> size 500x400 and size setting 250x200 in fo, the
> PDFXObject.output method outputs object info to pdf are,  for
> png in SVG:
> ++++++++++++++++
> 6 0 obj
> <</Type /XObject
> /Subtype /Image
> /Name /Im1
> /Length 49745
> /Width 1500
> /Height 1200
> /BitsPerComponent 8
> /ColorSpace /DeviceRGB
> /Mask [255 255 255 255 255 255]
> /Filter [ /ASCII85Decode /FlateDecode ]
> >>
> ++++++++++++++++++++++++
> and for external png is
> -------------------------
> 6 0 obj
> <</Type /XObject
> /Subtype /Image
> /Name /Im1
> /Length 26341
> /Width 500
> /Height 
> /BitsPerComponent 8
> /ColorSpace /DeviceRGB
> /Filter [ /ASCII85Decode /FlateDecode ]
> >>
> ---------------------------
> So the object size is different and the object length is
> different. Thus the question is how to make the PDFGraphics2D
to
> create the same data as JimiImage.
> 
> Any help is greatly appreciated. 
> 
> Jay 
> 
> 
> ================================================
> List:       fop-user
> Subject:    Re: Problem with scaling png image file in svg
> From:       Chris Bowditch <bowditch_chris () hotmail ! com>
> Date:       2004-02-12 9:55:10
> Message-ID: <402B4D7E.7060401 () hotmail ! com>
> [Download message RAW]
> 
> Jay Chiu wrote:
> 
> > Chris and Thomas,
> > 
> > Can you please give me some help? Please tell me which
files
> I
> > should change to solve the problem.
> 
> I have run your sample, and the PNG files referenced by 
> fo:external-graphic are indeed much better quaility than
those
> embedded 
> in SVG using svg:image. I then tried running FOP using -awt
> option 
> instead of generating a PDF and found that the quality of the
> PNG files 
> in fo:external-graphic are bad. That is because the AWT
renderer
> 
> probably uses the PDFGraphics2D.drawImage method that you
> mention.
> 
> I only saw part of Thomas's response, in which he seems to be
> implying 
> that the problem is in Batik, but it does seem that there are

> defficiencies in FOP's image handling algorithms. I believe
the
> images 
> look okay in the PDF Renderer because responsibility for
> actually 
> rendering the image is passed to acrobat reader. FOP just
> inserts the 
> image into the PDF. I dont know if theres a way to tell the
PDF
> 
> transcoder to do the same.
> 
> Perhaps one of the more experienced committers can shed some
> more light 
> on this matter.
> 
> Chris
> 
> 
> 
> 
> 
> ________________________________________________
> Get your own "800" number
> Voicemail, fax, email, and a lot more
> http://www.ureach.com/reg/tag
> 
> 
> ---- On Wed, 11 Feb 2004, Jay Chiu (jaychiu@ureach.com)
wrote:
> 
> > Chris and Thomas,
> > 
> > Can you please give me some help? Please tell me which
files
> I
> > should change to solve the problem.
> > 
> > Thanks a lot.
> > 
> > Jay
> > 
> > 
> > ============================================
> > 
> > List:       fop-user
> > Subject:    Re: Re: Problem with scaling png image file in
> svg
> > From:       Jay Chiu <jaychiu () ureach ! com>
> > Date:       2004-02-10 5:13:26
> > 
> > I think changing org.apache.fop.svg.PDFGraphics2D class may
> > solve the image quality issue. Because PDFGraphics2D class
> > hangles the image drawing. Can Fop developer please give me
> > some
> > help?
> > 
> > I tried to debug through fop with batik and find the call
> stack
> > for handling my png image is as following:
> > 
> > (1)org.apache.fop.svg.PDFGraphics2D.drawImage(Image img,
int
> x,
> > int y,ImageObserver observer)
> >
>
(2)org.apache.batik.ext.awt.image.GraphicsUtil.drawImag(Graphics2D
> > g2d, CachableRed cr):152
> >
>
(3)org.apache.batik.ext.awt.image.GraphicsUtil.drawImag(Graphics2D
> > g2d, CachableRed cr):439
> > (4)org.apache.batik.gvt.primitivePaint(Graphics2D g2d):92
> >
(5)org.apache.batik.gv.AbstractGraphicsNode.paint(Graphics2D
> > g2d):485
> >
>
(6)org.apache.batik.gvt.CompositeGraphicsNode.primitivePaint(Graphics2D
> > g2d):130
> >
(7)org.apache.batik.gv.AbstractGraphicsNode.paint(Graphics2D
> > g2d):485
> > (8)org.apache.batik.gvt.ImageNode.paint(Graphics2D g2d):34
> > org.apache.batik.gv.AbstractGraphicsNode.paint(Graphics2D
> g2d)
> > 
> > From the call stack info, it is clear that PDFGraphics2D
> > handles
> > the actual external image drawing. Can someone change
> > PDFGraphics2d to use the same approach to handle external
> image
> > file as other image handling code in FOP does?
> > 
> > Thanks.
> > 
> > Jay
> > 
> > > ---- On Sat, 07 Feb 2004, Jay Chiu (jaychiu@ureach.com)
> > wrote:
> > > 
> > > Thanks Thomas,
> > >  
> > > I guess anyone who includes images in SVG may get the
same
> > > problem. 
> > > 
> > > We are delivering a report tool to client and the client
is
> > > complaining about the chart quality in pdf. Thus we are
in
> a
> > > hurry to solve this isse. 
> > > 
> > > If someone has already written some code to solve this
> issue,
> > > please forward me some of your code.
> > > 
> > > If it is not too difficult, can you please give me some
> hint
> > and
> > > tell me which file should be changed? I guess probably we
> may
> > > take some fop's code to solve this issue, becuase the
> > > subsampling works fine in Fop.
> > > 
> > > Thanks a lot.
> > >  
> > > Jay
> > > 
> > > > ==============================================
> > > > Subject: Re: Problem with scaling png image file in svg

> > > > From: Thomas DeWeese <Thomas.DeWeese@Kodak.com> 
> > > > Date: Fri, 06 Feb 2004 06:25:45 -0500 
> > > > To: batik-dev@xml.apache.org 
> > > > 
> > > >
> > >
> >
>
--------------------------------------------------------------------------------
> > > > 
> > > > Jay Chiu wrote:
> > > > 
> > > > > I tried with Batik Squiggle for the png images. If I
> does
> > > not
> > > > > use <g transform="scale(xxx)">, the png image looks
> good
> > in
> > > > the
> > > > > GUI, it does get scaled properly. But image with
> scale()
> > > > > transform attribute losses quality, and the png file
> > > > generated
> > > > > by Squiggle is in bad quality. 
> > > > 
> > > >     The problem is that you are asking to subsample the
> > image
> > > > too much.  The large image is reduced by 5x the small
by
> > 10x.
> > > > Batik does not prefilter for large subsample values so
> you
> > > > 'loose' pixels with subsample values this high and the
> > result
> > > > is aliasing effects.
> > > > 
> > > >     If anyone wants to write/contribute a block average
> or
> > > > better
> > > > a true prefiltered resample operation I'm sure it would
> be
> > > > appreciated.  I can help with plugging it into Batik in
> the
> > > > right spot.
> > > > 
> > > > > I am also sending the email to batik-user mail list.
> Hope
> > > > Batik
> > > > > team can also help.
> > > > > 
> > > > > Attache please find a svg file , a source png file
and
> > > > > generated
> > > > > png file.
> > > > > 
> > > > > Thanks a lot.
> > > > > 
> > > > > Jay
> > > > > 
> > > > 
> > > > 
> > > > 
> > > > ________________________________________________
> > > > Get your own "800" number
> > > > Voicemail, fax, email, and a lot more
> > > > http://www.ureach.com/reg/tag
> > > > 
> > > > 
> > > 
> > > 
> > > 
> > 
> > 
> > ________________________________________________
> > Get your own "800" number
> > Voicemail, fax, email, and a lot more
> > http://www.ureach.com/reg/tag
> > 
> >
>
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