---
name: "im_piocheck"
section: "3"
platform: "linux"
package: "libvips-dev"
version: "7.20.7-1+b3"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/im_piocheck"
---

# im\_piocheck(3)

checks image descriptors for PIO

## NAME

im\_pincheck, im\_poutcheck, im\_piocheck - checks image descriptors for  PIO

## SYNOPSIS

**#include \<vips/vips.h\>**

int im\_pincheck( in )\
 IMAGE \*in;

int im\_poutcheck( out )\
 IMAGE \*out;

**int im\_piocheck( in, out)**\
 **IMAGE \*in, \*out;**

## DESCRIPTION

**[im\_pincheck(3)](/im_pincheck/3.md)** checks that an image descriptor is suitable for PIO input. If the descriptor is  IM\_OPENOUT and the descriptor has been written to, it is automatically \`rewound,' that is, it is closed and reopened as an IM\_MMAPIN descriptor.

[im\_poutcheck(3)](/im_poutcheck/3.md) checks that a descriptor is suitable for PIO output.

[im\_piocheck(3)](/im_piocheck/3.md) simply calls in\_pincheck(3) for image in and [im\_poutcheck(3)](/im_poutcheck/3.md) for image out.

## RETURN VALUE

All functions returns 0 on success and -1 on error.

## SEE ALSO

[im\_generate(3)](/im_generate/3.md), [im\_open(3)](/im_open/3.md).

## COPYRIGHT

National Gallery

## AUTHOR

J. Cupitt - 23/7/93