Can smallest and largest pixel value be changed?

[yuhong]

Hi, everyone,

I have a question about the smallest and largest pixel value: if they can be changed manually or calculated automatically based on the pixel data?

I am trying to do some pixel processing work, first I read the original pixel data from a dicom file and then do pixel calculation, after that write back the pixel data. I also calculate the smallest and largest pixel value of the resulting pixel data and write back the new smallest and largest pixel value. But when I checked the resulting image again, I found the smallest and largest pixel value were not changed.

That means one does not need to change these two values manually?

Can anyone help me?

Thanks in advance.

Yuhong

here is the code:

Code: Select all

DcmFileFormat fileformat;
fileformat.loadFile( "original.dcm");
DcmDataset *ds = fileformat.getDataset();

ds->putAndInsertUint16( DCM_SmallestImagePixelValue, 100 );
ds->putAndInsertUint16( DCM_LargestImagePixelValue, 1000 );

fileformat.saveFile( "result.dcm" );

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[Jörg Riesmeier]

The helper method putAndInsertUint16() currently does not support the internal VR "xs" of these two attributes (which is US or SS). That means you have to create the DcmUnsignedShort element manually:

Code: Select all

DcmElement *us = new DcmUnsignedShort(DcmTag(DCM_SmallestImagePixelValue, EVR_US));
if (us != NULL)
{
   us->putUint16(100);
   ds->insert(us, OFTrue /*replaceOld*/);
}

We'll probably enhanced the helper methods for Uint16 and Sint16 in this regard for the next release.

Btw, you should always check the return value of the methods you're using.

[yuhong]

Hi, Riesmeier,

I tried and it worked.

Thank you very much!

Have a nice day!

Yuhong
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