Complete white image with 6.8.7

[sireeshala]

Recently i have updated the image magick version to 6.8.7
i am using the bellow set of code to convert my image from jpg to tiff

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Image image;
	image.read( "case.jpg" );
	image.magick("TIFF");
        image.compressType(Group4Compression);
        image.type(BilevelType);
        image.write("case_1.tiff");

I am getting a complete white image .
The same image used to work fine with 6.8.2 version .Are there any changes particular to this issue?

the image is at https://www.dropbox.com/s/0sjy8uvc07f1yww/case.jpg

[fmw42]

I get the same using IM 6.8.7.5 Q16 Mac OSX command line

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convert case.jpg -compress group4 -type bilevel tmp.tif

or

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convert case.jpg -type bilevel tmp.tif

But this works fine

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convert case.jpg -threshold 50% -compress group4 tmp.tif

[sireeshala]

But its worked fine with out adding threshold value in 6.8.2
is this introduced in latest version ?
is there any specific criteria for an image to add the threshold value?

[fmw42]

I suspect there was a bug introduced somewhere between these versions.

[sireeshala]

What is the latest version of imageMagick?
I am using 6.8.7 dowloaded from http://www.imagemagick.org/script/insta ... hp#windows ImageMagick-windows.zip
is there any version available other than this?

[fmw42]

IM 6.8.7.6

see
http://www.imagemagick.org/script/binary-releases.php

convert -version

should tell you exactly what version you have

[dlemstra]

I just tried the latest beta and this produces a white image for me on windows.

[fmw42]

convert case.jpg -compress group4 -type bilevel tmp.tif

produces a white image for me, too, on 6.8.7.6 Q16 Mac OSX

[sireeshala]

convert case.jpg -compress group4 -type bilevel tmp.tif

But this works fine on windows mechine with version 6.8.2-4.

Only the latest versions giving the white image.

[sireeshala]

Is this a Bug or a new property "threshold" introduced to the latest versions?
can any one confirm on this ?

[fmw42]

-threshold is just a different way to get a binary image result. The threshold will change where the spit is between white an black in the image. It is not a requirement. The problem you are having is likely a bug. I only added -threshold to give you an alternate until this gets fixed.

[snibgo]

Group4 is a method for compressing images that contain only black and white. If the image contains other colours, IM needs to reduce it first. I don't suppose this reduction is well-defined, so is always subject to variations in methods used by IM to reduce colours. So it would seem better to always do the explicit reduction first.

[sireeshala]

I only added -threshold to give you an alternate until this gets fixed.

Is there any estimated dates to get that fixed ?

Basically we are using this from a bat file so we cant particulary change the the command for a single image every time .

[magick]

Try

• convert case.jpg -normalize -dither none -type bilevel -compress group4 tmp.tif

We will take a closer look at the bilevel algorithm, maybe we can get it to work without normalizing.

[sireeshala]

But How its worked with 6.8.2-4 .
And how much time it will take to get an update on this issue