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Antialiasing fails w/ Convert to Bitmap

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coreltom posted on Sat, Mar 6 2010 8:22

Weird. Import an image, scale it down (make it remarkably tiny like a stamp) and convert to bitmap @ 300 dpi + Antialiasing "on". The image becomes terribly pixellated. :o As a workaround, Resample Image works but then, why do we have Antialiasing on convert to bitmap options? Only for vectoral stuff? It should be able to interpolate the image pixels as well...

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Top 10 Contributor
Brisbane Australia
Male
Verified by coreltom

That certainly need to go on the list. Consider it done.

Yani

Ned's Mother -- You gotta help us, Doc. We've tried nothing and we're fresh out of ideas!
( The Simpsons, Hurricane Neddy -- Season:8 Episode:8 First Aired:12/29/1996 )

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Top 10 Contributor
Brisbane Australia
Male
Suggested by Yani

I checked to be sure it works perfectly. Not enough pixels is not enough pixels. Anti-aliasing only smooths the image in that case and stops pixels from posterisation.

Yani

Ned's Mother -- You gotta help us, Doc. We've tried nothing and we're fresh out of ideas!
( The Simpsons, Hurricane Neddy -- Season:8 Episode:8 First Aired:12/29/1996 )

Thanks! But, I've forgotten to add something. Could you please rotate the image a bit and try again? I think it's the rotation it cannot handle. :(

Top 10 Contributor
Brisbane Australia
Male
Verified by coreltom

That certainly need to go on the list. Consider it done.

Yani

Ned's Mother -- You gotta help us, Doc. We've tried nothing and we're fresh out of ideas!
( The Simpsons, Hurricane Neddy -- Season:8 Episode:8 First Aired:12/29/1996 )

Thanks for confirming!

Top 25 Contributor
Sweden
Male

coreltom:
Resample Image works but then, why do we have Antialiasing on convert to bitmap options?
The issue may be valid but I would like to point out that when you resize or rotate a bitmap in Draw is still 100% intact. No pixels are moved or removed in any way.
If you resample a rotated bitmap, it is performed on the non rotated original (check rotation angle).
If you instead convert to bitmap, Draw creates an entirely new non rotated bitmap, so it's a completely different calculation.

/Ronny

Yani, any idea why this is not fixed in X5SP1? :(

Top 25 Contributor
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coreltom:
Yani, any idea why this is not fixed in X5SP1? :(
Probably because there is nothing to fix.
As I said in my previous answer a rotated image in Draw is still 100% intact. It is rotated for sure but not changed in any way regarding the individual pixels.
If you resample like you describe, it will decrease the number of pixels but it will be performed on the original (non-rotated) bitmap, while Convert to Bitmap creates an entirely new bitmap based on the rotated one.
Two different things and most likely Convert to Bitmap is doing as good as it can during the circumstances.

/Ronny

Yani, how long will it take to fix this? :) Still not fixed in SP2...

Top 25 Contributor
Sweden
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Please read my previous posts. It will most likely never be fixed because it isn't broken.

If this is something that you do a lot, try doing it the other way around:
Scale the bitmap down to "stamp size", convert to a 300 dpi bitmap and then rotate it.
As long as you keep it inside Draw the pixels will be rotated and it looks pretty good on screen.
If you need to export out of Draw as a bitmap, the image must be converted again, either with Convert to Bitmap or on Export, but either way the result gets slightly better than trying to convert a downscaled and rotated bitmap in one step.

/Ronny

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