Performance ping large miff

[snibgo]

IM v6.9.5-3 on Windows 8.1.

"identify -ping x.miff" for large miff files is very slow.

Code: Select all

f:\web\im>timec %IM%convert -size 7000x7000 gradient: x.png

TimeC c:\im\ImageMagick-6.9.5-3-Q16\convert -size 7000x7000 gradient: x.png
Seconds: 4.28

f:\web\im>timec %IM%convert -size 7000x7000 gradient: x.miff

TimeC c:\im\ImageMagick-6.9.5-3-Q16\convert -size 7000x7000 gradient: x.miff
Seconds: 3.02

f:\web\im>timec %IM%identify -ping x.png
x.png PNG 7000x7000 7000x7000+0+0 16-bit sRGB 118KB 0.000u 0:00.000

TimeC c:\im\ImageMagick-6.9.5-3-Q16\identify -ping x.png
Seconds: 0.03

f:\web\im>timec %IM%identify -ping x.miff
x.miff MIFF 7000x7000 7000x7000+0+0 16-bit TrueColor sRGB 294MB 0.234u 0:00.452

TimeC c:\im\ImageMagick-6.9.5-3-Q16\identify -ping x.miff
Seconds: 4.84

It takes longer to "identify -ping x.miff" than it does to create it!

[snibgo]

I've discovered that "convert -ping x.miff info:" works more speedily.

Code: Select all

f:\web\im>timec %IM%convert -ping x.miff info:
x.miff MIFF 7000x7000 7000x7000+0+0 16-bit TrueColor sRGB 294MB 0.203u 0:00.202

TimeC c:\im\ImageMagick-6.9.5-3-Q16\convert -ping x.miff info:
Seconds: 0.45

I don't know why "identify" takes ten times as long as "convert". Even without "-ping", convert is quicker.

[magick]

Use this command instead:

• identify -ping 'x.miff[0]'

[snibgo]

Yes, that's better. Instead of 4.5 seconds, it's down to 0.03 seconds. But there's only one image, so it shouldn't make any difference, should it?