# Open RGB Explicit Little endian Dicom Image - DICOM

This is a discussion on Open RGB Explicit Little endian Dicom Image - DICOM ; Hi I am trying to open RGB Explicit Little endian Dicom Image.Which Tag information shows that this is a 8 bit image.Its transfer syntex is "1.2.840.10008.1.2.1" ,Samples Per Pixel=3, I am little confuse that 8bit allocation means" 8-bit for red,8-bit ...

# Thread: Open RGB Explicit Little endian Dicom Image

1. ## Open RGB Explicit Little endian Dicom Image

Hi
I am trying to open RGB Explicit Little endian Dicom Image.Which Tag
information shows that
this is a 8 bit image.Its transfer syntex is "1.2.840.10008.1.2.1"
,Samples Per Pixel=3,
I am little confuse that 8bit allocation means" 8-bit for red,8-bit
fro green,8-bit for blue"
Or 3 bit for red,3bit for green ,2 bit for blue. please gide me how to
proceed to open this type of image. What Tag information needed for
open this image.

2. ## Re: Open RGB Explicit Little endian Dicom Image

Hello Neeraj,

Neeraj wrote:

> this is a 8 bit image.Its transfer syntex is "1.2.840.10008.1.2.1"
> ,Samples Per Pixel=3,

There you go: 8 bit allocated = 1 Byte per pixel, *but* 3 Samples per
pixel: 1 "Overlay" red, one green, one blue ...

HTH,

Peter

3. ## Re: Open RGB Explicit Little endian Dicom Image

Can your tell me wat is the photometric interpretation... just for my
own info...
Thanks

Neeraj wrote:
> Hi
> I am trying to open RGB Explicit Little endian Dicom Image.Which Tag
> information shows that
> this is a 8 bit image.Its transfer syntex is "1.2.840.10008.1.2.1"
> ,Samples Per Pixel=3,
> I am little confuse that 8bit allocation means" 8-bit for red,8-bit
> fro green,8-bit for blue"
> Or 3 bit for red,3bit for green ,2 bit for blue. please gide me how to
> proceed to open this type of image. What Tag information needed for
> open this image.

4. ## Re: Open RGB Explicit Little endian Dicom Image

Its photometric interpretation =RGB

yogi wrote:
> Can your tell me wat is the photometric interpretation... just for my
> own info...
> Thanks
>
> Neeraj wrote:
> > Hi
> > I am trying to open RGB Explicit Little endian Dicom Image.Which Tag
> > information shows that
> > this is a 8 bit image.Its transfer syntex is "1.2.840.10008.1.2.1"
> > ,Samples Per Pixel=3,
> > I am little confuse that 8bit allocation means" 8-bit for red,8-bit
> > fro green,8-bit for blue"
> > Or 3 bit for red,3bit for green ,2 bit for blue. please gide me how to
> > proceed to open this type of image. What Tag information needed for
> > open this image.

5. ## Re: Open RGB Explicit Little endian Dicom Image

Neeraj wrote:
> Hi
> I am trying to open RGB Explicit Little endian Dicom Image.Which Tag
> information shows that
> this is a 8 bit image.Its transfer syntex is "1.2.840.10008.1.2.1"
> ,Samples Per Pixel=3,
> I am little confuse that 8bit allocation means" 8-bit for red,8-bit
> fro green,8-bit for blue"
> Or 3 bit for red,3bit for green ,2 bit for blue. please gide me how to
> proceed to open this type of image. What Tag information needed for
> open this image.

Your juxtapositioning of the transfer syntax and samples per pixel=3 in
the same sentence could possibly be interpreted as indicating you
somehow think the transfer syntax conveys some parsing of multiple
samples per pixel. When using JPEG compression of RGB color images, the
logic to set up the JPEG compression would likely use the DICOM Tag
(0028,0002) - samples per pixel to set up the correct JPEG header
markers (since the JPEG alogrithm is normally setup to compress the R,
G, and B components of a color image as if each component was a
separate greyscale 8-bit image).
However - the transfer syntax you cite is not a JPEG compression
transfer syntax. Instead it is Explict VR Little Endian (as you
stated); but your citation of a transfer syntax is irrelevant to the
discussion of the pixel encoding.
What you need to look at are
(0028,0100) - Bits Allocated
(0028,0101) - Bits Stored
(0028,0102) - High Bit
(0028,0002) - Samples per pixel

In the DICOM Standard Part 3, Bits Allocated Definition says "Number of
bits allocated for each pixel sample. Each sample shall have the same
number of bits allocated. See PS 3.5 for further explanation."

Also the definition of Sample Per Pixel says
"Samples per Pixel (0028,0002) is the number of separate planes in this
image. One, three, and four image planes are defined. Other numbers of
image planes are allowed, but their meaning is not defined by this
Standard.
For monochrome (gray scale) and palette color images, the number of
planes is 1. For RGB and other three vector color models, the value of
this attribute is 3. For four vector color models, the value of this
attribute is 4."

Also, under the definition of Photometric Interpretation, the coded
term RGB has the following information
"RGB = Pixel data represent a color image described by red, green, and
blue image planes. The minimum sample value for each color plane
represents minimum intensity of the color. This value may be used only
when Samples per Pixel (0028,0002) has a value of 3"

Bottom line, although you haven't listed these attributes - your images
are almost certainly 24 bit, 3 component, 8-bits per pixel color sample
images. In your case Bits Stored and Bits Allocated should be the same.

6. ## Re: Open RGB Explicit Little endian Dicom Image

Hello again,

Peter B Schmidt wrote:
> Hello Neeraj,
> There you go: 8 bit allocated = 1 Byte per pixel, *but* 3 Samples per
> pixel: 1 "Overlay" red, one green, one blue ...

after reading some other replies, I think my answer has to be clarified:
you have 3 Image planes (Red, Green, Blue) encoded in RGB with 1 Byte
per pixel *in each plane* - this means: 8 bit Red, 8 bit Green, 8 bit
Blue results in 24 bit per pixel - which is bits per pixel multiplied by
samples per pixel.

Does this make it a little less obscure to you?

Kind regards,

Peter