What is the parallel of magick autolevel in pyvips?

[deepankarpal1985]

What is the parallel of magick autolevel in pyvips?

[jcupitt]

Try image.scaleimage().

https://libvips.github.io/pyvips/vimage.html#pyvips.Image.scaleimage

Main docs:

https://jcupitt.github.io/libvips/API/current/libvips-conversion.html#vips-scale

[deepankarpal1985]

Tried that, can't write to a png file post that

unable to call VipsForeignSavePngFile vipspng: out of order read at line 240 vips2png: unable to write "t2.png"

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From: John Cupitt [email protected] Sent: Wednesday, July 10, 2019 10:50 AM To: libvips/pyvips Cc: Deepankar Pal; Author Subject: Re: [libvips/pyvips] What is the parallel of magick autolevel in pyvips? (#108)

Try image.scaleimage().

https://libvips.github.io/pyvips/vimage.html#pyvips.Image.scaleimage

Main docs:

https://jcupitt.github.io/libvips/API/current/libvips-conversion.html#vips-scale

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[jcupitt]

You've opened your image in sequential mode. Remove the access= from the new_from_file.

[jcupitt]

... to explain, scale has to scan the image to find the min and max before it can scale the image levels. But if the image has been opened in streaming mode, you can only read each pixel once. So when the save to PNG operation starts, the image has already been scanned and there are no pixels left.

[deepankarpal1985]

Thanks

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From: John Cupitt [email protected] Sent: Wednesday, July 10, 2019 11:06 AM To: libvips/pyvips Cc: Deepankar Pal; Author Subject: Re: [libvips/pyvips] What is the parallel of magick autolevel in pyvips? (#108)

... to explain, scale has to scan the image to find the min and max before it can scale the image levels. But if the image has been opened in streaming mode, you can only read each pixel once. So when the save to PNG operation starts, the image has already been scanned and there are no pixels left.

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