What's the canonical way to get the RAM size of a PNG

[jack-mann]

If I do a

Code: Select all

convert img.png    out.bmp

I get for a 20500x8000 img.png a 500M out.bmp

So can I conclude that when imagmagick reads the img.png in it uses about 500M RAM?

[magick]

Resource requirements for a typical image is 4 x width x height. The resource can be memory or disk depending on your resource limits. Add -limit memory 2MB, for example, to limit the amount of allowed memory to 2MB. If this limit is exceeded, pixels are pushed to disk. The tradeoff is that disk access is 1000x slower than memory access. See http://www.imagemagick.org/script/archi ... .php#cache for details.

[glennrp]

Resource requirements for a typical image is 4 x width x height.

It's 4 times width times height times bytes_per_sample. bytes_per_sample depends on how you built ImageMagick. It's 1 in a Q8 build, 2 in a Q16, 4, in a Q32, etc.

[snibgo]

So, in the OP's example of 20500x8000 pixels, assuming Q16, we need 8 bytes/pixels, so 1.3GB of memory.