Command line copy an image file to the clipboard in Mac OS X. See first comment for install instructions.

impbcopy.m

#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#import <unistd.h>
BOOL copy_to_clipboard(NSString *path)
{
  // http://stackoverflow.com/questions/2681630/how-to-read-png-image-to-nsimage
  NSImage * image;
  if([path isEqualToString:@"-"])
  {
    // http://caiustheory.com/read-standard-input-using-objective-c 
    NSFileHandle *input = [NSFileHandle fileHandleWithStandardInput];
    image = [[NSImage alloc] initWithData:[input readDataToEndOfFile]];
  }else
  { 
    image =  [[NSImage alloc] initWithContentsOfFile:path];
  }
  // http://stackoverflow.com/a/18124824/148668
  BOOL copied = false;
  if (image != nil)
  {
    NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
    [pasteboard clearContents];
    NSArray *copiedObjects = [NSArray arrayWithObject:image];
    copied = [pasteboard writeObjects:copiedObjects];
    [pasteboard release];
  }
  [image release];
  return copied;
}

int main(int argc, char * const argv[])
{
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
  if(argc<2)
  {
    printf("Usage:\n\n"
      "Copy file to clipboard:\n    ./impbcopy path/to/file\n\n"
      "Copy stdin to clipboard:\n    cat /path/to/file | ./impbcopy -");
    return EXIT_FAILURE;
  }
  NSString *path= [NSString stringWithUTF8String:argv[1]];
  BOOL success = copy_to_clipboard(path);
  [pool release];
  return (success?EXIT_SUCCESS:EXIT_FAILURE);
}

// compile command
// gcc -Wall -g -O3 -ObjC -framework Foundation -framework AppKit -o impbcopy impbcopy.m
// usage:
// impbcopy image.png
// or
// cat img.jpg | impbcopy

impbpaste.m

#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#import <unistd.h>

@interface NSImage(saveAsPNGWithName)
- (void) saveAsPNGWithName:(NSString*) fileName;
@end

@implementation NSImage(saveAsPNGWithName)

- (void) saveAsPNGWithName:(NSString*) fileName
{
    // Cache the reduced image
    NSData *imageData = [self TIFFRepresentation];
    NSBitmapImageRep *imageRep = [NSBitmapImageRep imageRepWithData:imageData];
    NSDictionary *imageProps = [NSDictionary dictionaryWithObject:[NSNumber numberWithFloat:1.0] forKey:NSImageCompressionFactor];
    imageData = [imageRep representationUsingType:NSPNGFileType properties:imageProps];
    [imageData writeToFile:fileName atomically:NO];        
}

@end

BOOL paste_from_clipboard(NSString *path)
{
  // http://stackoverflow.com/a/18124824/148668
  NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
  NSArray *classArray = [NSArray arrayWithObject:[NSImage class]];
  NSDictionary *options = [NSDictionary dictionary];
  BOOL ok = [pasteboard canReadObjectForClasses:classArray options:options]; 
  if(ok)
  {
    NSArray *objectsToPaste = [pasteboard readObjectsForClasses:classArray options:options];
    NSImage *image = [objectsToPaste objectAtIndex:0];
    // http://stackoverflow.com/a/3213017/148668
    [image release];
  }else
  {
    printf("Error: Clipboard doesn't seem to contain an image.\n");
  }
  return ok;
}

int main(int argc, char * const argv[])
{
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
  if(argc<2)
  {
    printf("Usage:\n\n"
      "Paste clipboard to file:\n    ./impbcopy path/to/file\n\n");
    return EXIT_FAILURE;
  }
  NSString *path= [NSString stringWithUTF8String:argv[1]];
  BOOL success = paste_from_clipboard(path);
  [pool release];
  return (success?EXIT_SUCCESS:EXIT_FAILURE);
}

// compile command
// clang -Wall -g -O3 -ObjC -framework Foundation -framework AppKit -o impbpaste impbpaste.m
// usage: impbpaste image.png

Original post: http://www.alecjacobson.com/weblog/?p=3816