Re: Image Resolution
Re: Image Resolution
- Subject: Re: Image Resolution
- From: Quincey Morris <email@hidden>
- Date: Mon, 18 Oct 2010 11:55:41 -0700
On Oct 18, 2010, at 04:37, Amy Heavey wrote:
> The source images are not generated by us, they are from a variety of surces, and are generally 200pixels + on each side, however sometimes they are 72 dpi, and sometimes they are 300dpi. Even if an aimage is 450pixels square, when it is set as 300 dpi it's reduced too small when my app reduces it it to fit a 75pixel square area.
>
> I know this is to do with the bitmapRepresentation, but I can't work out how to change it. If I was doing this in photoshop I'd be keeping the actual pixel count, but changing the resolution from 300 to 72 for these images.
>
> Can anyone point me in the right direction? Here's the code I'm using at the moment:
>
> while ((imgPath = [imageLoop nextObject])) {
> NSImage *img = [[NSImage alloc]initWithContentsOfFile:imgPath];
> [targetImage lockFocus];
>
> [img drawInRect:NSMakeRect(x,y,75,75) fromRect:NSMakeRect(20,20,0,0) operation:NSCompositeCopy fraction:1];
What does "too small" mean? Are you saying that your original image is being drawn somewhere inside your 75-pixel square, failing to fill it completely?
Also, I don't understand the intended significance of your 'fromRect:NSMakeRect(20,20,0,0)' parameter. This should either be the part of the original image you want to transfer to the destination, or NSZeroRect to copy the whole thing.
If you're copying the whole image, I can't see that the "resolution" (in the sense of "dpi") has any significance to 'drawInRect:...'. It really only comes into play when relating the absolute (in points) size of two different images or contexts. You can always adjust the (effective) resolution of a NSImage by calling 'setSize:' with the absolute size you want. This does not change the pixel size of the underlying representation.
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