Image Quality

[JHEarcht]

In VWA9.5.1 (Windows98se) I export an object as TIF image with 300dpi selected. When I reimport the image it looks terrible. The original straight lines are now jagged.

I tried the same thing in another graphic program and the re-imported file looks just like the original.

My question is this: is VW lying to me when it says the file is being exported at 300dpi? Does VW always export images at 72dpi regardless of the setting I select? Is there anything I can do to export sharp-edged graphics from VW?

[Kristen]

Image quality is a combination of dpi and image size. You have to change both to get the quality of image you want. For example, if you want a 300dpi image that's 6"x8", you have set the height to 1800 and the width to 2400.

Some programs let you set the image size in inches and then change the dpi to change image quality, which seems more intuitive to me. However, VW (at least VW8 and 9; I haven't tried 10 yet) requires you to set the size in pixels. You can get the image quality you want... it just requires a little more math.

[ 01-21-2003, 05:57 PM: Message edited by: Kristen ]

[MikeB]

Kristins right, you have to set the pixel dimension. Something around 3000 pixels wide is usually pretty good.

Good Luck

[Guest]

VW imports image files and converts them to bitmaps.

That is probably why you are seeing a different on reimporting.

VW image file types are based on those QuickTime offers since our export is the QT engine.

PNG is a common file format support by QuickTime, thus VW and just about every other image viewing application.

It's the new file type used to replace the copywrite protected GIF format.

It allows for great compression and smooth edges resulting in a good image file.

[JHEarcht]

quote:

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Originally posted by Kristen:

Image quality is a combination of dpi and image size. You have to change both to get the quality of image you want. For example, if you want a 300dpi image that's 6"x8", you have set the height to 1800 and the width to 2400.

Some programs let you set the image size in inches and then change the dpi to change image quality, which seems more intuitive to me. However, VW (at least VW8 and 9; I haven't tried 10 yet) requires you to set the size in pixels. You can get the image quality you want... it just requires a little more math.

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[JHEarcht]

Kristen and MikeB,

Thanks for the feedback. My crude workaround has been to draw the object 10 times larger than the intended final size. But I still don't understand why an exported image can't be re-imported at the same size with the same quality as the original. Guess I'll have to pay closer atention to the pixel count.

[Guest]

A Tiff file is jagged by property.

An object in VW is not an image but a vector.

Using a different image format that is not jagged by nature might be a solution. A good image type to use is PNG.

By increasing the width and height, you increase the DPI, allowing for a better image.

Changing the DPI setting itself will have no affect on the object itself.

[JHEarcht]

Thanks,

I'll try a PNG file next time if VW supports that format.

However, my DRAWPLUS program seems to draw a metafile with both vectors and bitmaps. When I re-import the file as TIF or JPG it looks just like the original. There's still something here that I'm not getting.