Re: Tiff conversion
Re: Tiff conversion
- Subject: Re: Tiff conversion
- From: Ivan Salina Fernandes <email@hidden>
- Date: Sat, 11 Aug 2001 17:31:02 -0300
Dear Clyde,
Thank you for your great help. I found how to create an algorithm, and
it's working fine. But now I'm having a problem getting the bytes. When
the Tiff images have 300 dpi, my array goes out of memory (I'm using
java). So, I have to try two kinds of solution:
1- Find a solution for de out of memory error, or;
2- Convert the images to 72 dpi (using cocoa).
Can you help me ?
Thanks again.
Ivan
email@hidden
On Monday, August 6, 2001, at 02:07 PM, Clyde McQueen wrote:
On Monday, August 6, 2001, at 06:10 AM, Ivan Salina Fernandes wrote:
I created this second image, but I don't know where I can find this
standard conversion algotithm. Do you know ?
I did a quick search on Google and came up with this site; there are
probably more:
http://www.scriptmeridian.org/projects/tips/cmyktorgb.html
Also, I found this warning:
http://www.pixelphoto.com/html/cmyk_and_rgb.html
This "pixel by pixel" that you talked about means byte by byte ?!
Sort of. You'll have 3 bytes per pixel in the RGB space, and 4 bytes
for CMYK. They're either organized in planes (all the red together, all
of the green together, and all the blue together) or meshed (a red
byte, a green byte, a blue byte, and so on). You'll have to query the
image to find out what you have.
When you create the CMYK image you have to decide if you want 4 planes
or a single meshed plane. It probably depends on the application.
/Clyde
Thank you very much.
Ivan
email@hidden
On Friday, August 3, 2001, at 06:55 PM, Clyde McQueen wrote:
On Wednesday, August 1, 2001, at 02:33 PM, Ivan Salina Fernandes
wrote:
Dear friends,
I'm trying to convert a tiff image, from CMYK (4 components) to RGB
(3 components). I'm using Cocoa, but I couldn't find any kind of
"way" to do this. Can anybody HELP me ?
You'll have to do it yourself. Create a 2nd NSBitmapImageRep with 3
planes using the rather hairy method:
- (id)initWithBitmapDataPlanes:(unsigned char **)planes
pixelsWide:(int)width
pixelsHigh:(int)height
bitsPerSample:(int)bps
samplesPerPixel:(int)spp
hasAlpha:(BOOL)alpha
isPlanar:(BOOL)isPlanar
colorSpaceName:(NSString *)colorSpaceName
bytesPerRow:(int)rowBytes
bitsPerPixel:(int)pixelBits
Then walk the source & destination data pixel by pixel and convert
CMYK to RGB using the standard conversion algorithm.
/Clyde