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https://issues.apache.org/jira/browse/PDFBOX-5898?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17900584#comment-17900584
]
Tilman Hausherr edited comment on PDFBOX-5898 at 11/24/24 4:29 PM:
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I have been able to reproduce the effect:
{code:java}
public class PDFBOX5898
{
public static void main(String[] args) throws IOException
{
int factor = 50; // effect should appear at 10; appears also at 15, 25,
50; not at 20 or 100
float step = 0.75f;
BufferedImage bim = new BufferedImage((int) (8 * factor * step), (int)
(8 * factor * step), BufferedImage.TYPE_INT_ARGB); // happens also with RGB
Graphics2D g = bim.createGraphics();
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON); // VALUE_ANTIALIAS_ON does it
g.setColor(new Color(0.35686f,0.60784f,0.83529f));
g.transform(AffineTransform.getScaleInstance(factor, factor));
for (float x = 0; x < bim.getWidth(); x += step)
{
for (float y = 0; y < bim.getHeight(); y += step)
{
GeneralPath linePath = new GeneralPath();
linePath.moveTo(x, y);
linePath.lineTo(x + 0.75f, y);
linePath.lineTo(x + 0.75f, y + 0.75f);
linePath.lineTo(x, y + 0.75f);
linePath.closePath();
g.fill(linePath);
}
}
g.dispose();
ImageIO.write(bim, "png", new File("bim.png"));
}
}
{code}
So it's the anti aliasing that does it. {{Pagedrawer.java}} has this:
{code:java}
Rectangle2D bounds = linePath.getBounds2D();
boolean noAntiAlias = isRectangular(linePath) && bounds.getWidth() > 1
&&
bounds.getHeight() > 1;
if (noAntiAlias)
{
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_OFF);
}
{code}
I've tried activating that part for bounds larger than 1x1 and got many
differences where the results looked worse, e.g. PDFBOX-1658.
was (Author: tilman):
I have been able to reproduce the effect:
{code:java}
public class PDFBOX5898
{
public static void main(String[] args) throws IOException
{
int factor = 50; // effect should appear at 10; appears also at 15, 25,
50; not at 20 or 100
float step = 0.75f;
BufferedImage bim = new BufferedImage((int) (8 * factor * step), (int)
(8 * factor * step), BufferedImage.TYPE_INT_ARGB); // happens also with RGB
Graphics2D g = bim.createGraphics();
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON); // VALUE_ANTIALIAS_ON one does it
g.setColor(new Color(0.35686f,0.60784f,0.83529f));
g.transform(AffineTransform.getScaleInstance(factor, factor));
for (float x = 0; x < bim.getWidth(); x += step)
{
for (float y = 0; y < bim.getHeight(); y += step)
{
GeneralPath linePath = new GeneralPath();
linePath.moveTo(x, y);
linePath.lineTo(x + 0.75f, y);
linePath.lineTo(x + 0.75f, y + 0.75f);
linePath.lineTo(x, y + 0.75f);
linePath.closePath();
g.fill(linePath);
}
}
g.dispose();
ImageIO.write(bim, "png", new File("bim.png"));
}
}
{code}
So it's the anti aliasing that does it. {{Pagedrawer.java}} has this:
{code:java}
Rectangle2D bounds = linePath.getBounds2D();
boolean noAntiAlias = isRectangular(linePath) && bounds.getWidth() > 1
&&
bounds.getHeight() > 1;
if (noAntiAlias)
{
graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_OFF);
}
{code}
I've tried activating that part for bounds larger than 1x1 and got many
differences where the results looked worse, e.g. PDFBOX-1658.
> Converting PDF to images using PDFBox results in unexpected outcomes.
> ---------------------------------------------------------------------
>
> Key: PDFBOX-5898
> URL: https://issues.apache.org/jira/browse/PDFBOX-5898
> Project: PDFBox
> Issue Type: Bug
> Affects Versions: 2.0.24
> Reporter: bai yuan
> Priority: Major
> Attachments: TilingPattern-2371731399394458-1000%.png,
> TilingPattern-2371731399416644-2000%.png, image-2024-11-12-15-45-48-011.png,
> test2.pdf
>
>
> Running the following code, many fine red lines appear in the image.
> {code:java}
> String pdfFilePath = path + "test2.pdf";
> String outputDir = path + "/out/";
> try {
> PDDocument document = PDDocument.load(new File(pdfFilePath));
> PDFRenderer pdfRenderer = new PDFRenderer(document);
> for (int page = 0; page < document.getNumberOfPages(); page++) {
> BufferedImage bim = pdfRenderer.renderImageWithDPI(page, 300,
> ImageType.RGB);
> ImageIO.write(bim, "PNG", new File(outputDir + "page-" +
> (page + 1) + ".png"));
> }
> document.close();
> System.out.println("PDF converted to images successfully.");
> } catch (Exception e) {
> e.printStackTrace();
> }
> {code}
> !image-2024-11-12-15-45-48-011.png!
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