[Dcmlib] FileHelper->GetImageData()

[Jean-Pierre ROUX]

At 21:54 -0400 4/09/05, Greg Book wrote:
>Thanks for the info. That function will be very helpful. So, what 
>happens if 'samples per pixel' is not 3? I would assume it's 1 when 
>its a monochrome image?

'Sample Per Pixel' is a mandatory Dicom field.
It can contain only 1 (monochrome image, or palette color image) or 3 
(RGB or YBR images)

> If thats the case, are monochrome images ever compressed, and if 
>so, how would they be read using gdcm.

Any kind of image may be compressed or not.
gdcm users don't have to worry about compression.
Just write, as for any image:

gdcm::File *f = new gdcm::File();
f->SetFileName(yourFileName);
f->Load(); // Load the header;

if (!f->IsReadable())
{
   --> stop everything :-(
}

gdcm::FileHelper *fh = new gdcm::FileHelper(f);
uint8_t *imageData;

imageData = fh->GetImageData();

The pixels are now loaded in memory, line by line, RGB, RGB, RGB ..., 
if it's a color image.

According to what you found in f, you decide how you must cast.

JP
 



>
>-Greg
>
>
>Jean-Pierre ROUX wrote:
>
>>At 14:04 -0400 2/09/05, Greg Book wrote:
>>
>>>I'm interested in using the GetImageData() function to read my 
>>>files instead of reading them by opening them and reading the 
>>>bytes. Once you've called this function and have an array of 
>>>unsigned integers... how is that array structured?
>>>Is it one byte for R, G, B? so 3 bytes per pixel? Then I assume 
>>>line breaks occur at pixel (3 byte) boundaries? So to read a 
>>>100x100pixel image, I'd take the first 300 bytes of the buffer 
>>>returned from GetImageData as the first line of the image, then 
>>>get the next 300 for the next line, and so on?
>>
>>
>>You're absolutely right.
>>In Dicom, there are 2 possibilities for RGB images :
>>- Storing 'Plane R + Plage G + Plane B'
>>- Storing pixels RGB RGB RGB ...
>>
>>We choosed to convert them as RGB RGB RGB ...
>>(we convert YBR to RGB too).
>>
>>Just be sure that field 'Samples per Pixel' value is 3.
>>JP
>>
>>>
>>>Thanks,
>>>Greg
>>>_______________________________________________
>>>Dcmlib mailing list
>>>Dcmlib at creatis.insa-lyon.fr
>>>http://www.creatis.insa-lyon.fr/mailman/listinfo/dcmlib
>>
>>
>> Jean-Pierre ROUX
>> CREATIS - CNRS UMR 5515, INSERM U 630
>> Laboratoire de Radiologie Experimentale
>> Hopital Cardiologique
>> 28 Avenue du Doyen LEPINE
>> B.P. Lyon-Montchat
>> 69394 Lyon Cedex 03
>>
>> Tel      : (+33) 04 72 35 74 12
>> Fax      : (+33) 04 72 68 49 16
>> URL      : http://www.creatis.univ-lyon1.fr
>> e-mail   : jpr at creatis.univ-lyon1.fr
>>

   Jean-Pierre ROUX
   CREATIS - CNRS UMR 5515, INSERM U 630
   Laboratoire de Radiologie Experimentale
   Hopital Cardiologique
   28 Avenue du Doyen LEPINE
   B.P. Lyon-Montchat
   69394 Lyon Cedex 03
 
   Tel      : (+33) 04 72 35 74 12
   Fax      : (+33) 04 72 68 49 16
   URL      : http://www.creatis.univ-lyon1.fr
   e-mail   : jpr at creatis.univ-lyon1.fr