Legacy ImageMagick Discussions Archive

Problem is solved — im forget added -clamp options for hdri version of convert.
With -clamp everything is fine.

Hi all. Im use imagemagick for resize images. This is original images http://pic.lg.ua/x/11/e864bd/677d8d3e.jpg This is my command line for resize. convert -depth 16 cec8fwqv4b8qxee3y5.jpg -colorspace RGB -filter Mitchell -sampling-factor 1x1 -thumbnail 139x231\! -background "#ffffff" -alpha ...

dimkalinux: The differences are very noticeable in your two screenshots (look, for example, at the corners, and the number 2 at bottom left). I'm having trouble, however, telling what the contribution of the filter is compared to USM's. Could you post the code? Resize /usr/local/bin/convert.hdri ...

If I get the drift of 2), I'd try "distort results sharpen up more naturally." Does this description sound accurate to you? Default distort produce some blurred images as and resize or as any other resize algo. But, with distort i can more accurately tune USM parameters and it produce less ...

I'm use -background #ffffff in all resize and i think it make all transparent pixels are white. is not? I'm read than images resized in IM with transparent preserve may cause that on Internet Explorer (maybe old version?) will display this transparent pixels as black. Cant testing because haven't IE ...

Not only pure cpu load may cause high Load Average - it may be high IO-wait (slow or bad tuned harddrive) or bad tuned webserver... too many reasons and no way to check it without ssh access to server. If u use Cpanel - its have not optimal performance of apache webserver, cpanel oriented on ...

99% photohosting services even dont use gamma aware scaling - and user happy. But differences very huge - if u can compare images. Im not shure that separately apha-channel processing produce huge differences. Maybe it complicated for practical realization in software, or slow. Im make little ...

u need well tune USM mask for different image size. I think it is not image size that you should be testing, but the scaling factor of the resize. Not shure - USM applied after resize for already scaled images. Why i need make differences for original size? For example: 1 case: scale 502x502 image ...

Can you give a demonstration of the effect you are trying to avoid, and the command you use? uch a demonstration would probably be more important as an example than the more normal, how to do it. Example better view on white background. Original http://pic.lluga.net/x/1/248770/347e2821.png Left ...

HDRI pixels can go negative or exceed the pixel range, generally 0-65535. You probably need to add -clamp in your workflow to restrict the pixel values to 0-65535. I think that in case when i save in non-float-able format like png/jpg truncate pixels range aka clamp make automatically. Ok, i try ...

Make test with HDRI version - it produce many tiny color errors in result.
Its normal for HDRI or report bug?

HDRI - http://pic.lluga.net/s/sifaS
Normal Q16 - http://pic.lluga.net/s/aXHFH

In latest version of IM PNG seems to be slow - u can try early version.

Another "funny" things with distort+USM. If your image have 1px contrast borders - after USM it can dissapear. For avoid this u need well tune USM mask for different image size. Like this // MIN SHARPING $sharpen_cmd_part = ' -unsharp 0x0.5+0.4+0.005 '; // if ($dst_size > ((250 * 250) + 1 ...

I test this.

-filter blur is worse for diagonal lines - when overall sharpnes is the same as USM 0.75 - on blur diagonal lines is very bad. Specialy when lines is contrast solid thin line.

After testing on different types of images: photo, screen-shots with text and others - i`m found that this parameters work best for me /usr/bin/convert ./322ca0b1.png -depth 16 -colorspace sRGB -auto-orient -alpha on -virtual-pixel transparent +distort Affine '0,0 0,0 %w,0 740,0 0,%h 0,650' -crop ...