DICOM vs JPEG and other things

[Daniel Juan Sanchez]

Hi to everybody:
I have to compare DICOM vs JPEG. I have doubts about whether it愀
possible this comparation since I think it愀 similar to compare Internet
vs HTML. I need to know if its comparable.
Anyway, perhaps from some point of view it愀 possible. Could anyone help
me?
More things, as you can realize I don愒 know the concepts of DICOM very
well. I悲 be vere grateful if someone could tell me the basis of DICOM
in few words and simply.
And the last doubts. I want to know what data format can be encapsulated
in a DICOM file. For example, is it possible BMP or GIF?
Finally, I know conversors JPEG to DICOM exists, but what do this
conversors do exactly? Do they eliminate the DICOM File Meta Information
(Header) simly and take the image (DICOM Data Set)?
Thanks
Dani

[Marco Eichelberg]

"Daniel Juan Sanchez" wrote:
> I have to compare DICOM vs JPEG. I have doubts about whether it´s
> possible this comparation since I think it´s similar to compare Internet

> vs HTML. I need to know if its comparable.

No, you cannot really compare DICOM and JPEG. JPEG is a standard that
defines a number of compression algorithms (both lossy and lossless). JPEG
is also often associated with the JFIF file format which encapsulates one
JPEG bitstream.

DICOM is a standard that covers information models for medical imaging,
client/service network protocols, storage media including file format and
much more.

If you just compare the two file formats, one could say the following:

- JPEG files (JFIF) contain a single monochrome or color still image and no
(standardised) meta information.

- DICOM files contain one or more monochrome or color images and a rich set
of standardised meta information explaining the context of the patient,
study, series, acquisition device etc. to which the image is related. The
image data inside the DICOM file can either be uncompressed (native) or
compressed. DICOM supports a number of compression algorithms, including
JPEG.

> And the last doubts. I want to know what data format can be encapsulated
> in a DICOM file. For example, is it possible BMP or GIF?

No, uncompressed DICOM image files have their own structure, which is not
compatible to BMP, and there is no counterpart for GIF, i.e. no LZW
compression for DICOM. However, the superior LZH compression (zip
compression) is available in DICOM.

> Finally, I know conversors JPEG to DICOM exists, but what do this
> conversors do exactly? Do they eliminate the DICOM File Meta Information
> (Header) simly and take the image (DICOM Data Set)?

When you convert from DICOM to JPEG, you completely eliminate all meta
information. If the DICOM image was already JPEG compressed internally, it
is rather trivial to convert it into a JFIF image, otherwise you have to
compress the native DICOM bitmap to JPEG.

Converting in the other direction requires you to add all the meta
information and, if the DICOM image should not be compressed, to decompress
the JPEG frame.

Hope this helps.
Marco Eichelberg

[Daniel Juan Sanchez]

THANK YOU VERY MUCH. ONLY ONE QUESTIONS.
COULD YOU TELL ME OTHERS FILE FORMATS DIFFERENT TO JPEG AND JPEG 2000 THAT CAN
BE ENCAPSULATED IN A DICOM FILE??
AND AGAIN. IT巽 A PLEASURE FIND PEOPLE AS YOU.
THANK YOU
DANI

Marco Eichelberg wrote:

> "Daniel Juan Sanchez" wrote:
> > I have to compare DICOM vs JPEG. I have doubts about whether it愀
> > possible this comparation since I think it愀 similar to compare Internet

[Marco Eichelberg]

"Daniel Juan Sanchez" wrote...

>
> COULD YOU TELL ME OTHERS FILE FORMATS DIFFERENT TO JPEG AND JPEG 2000 THAT
CAN
> BE ENCAPSULATED IN A DICOM FILE??

Strictly speaking, DICOM does not encapsulate file formats, but compressed
bitstreams - in fact for most algorithms supported in DICOM this means
almost but not quite the same thing. For example, the JPEG bitstream in
DICOM will not contain a JFIF header, as mentioned in my last post in this
thread.

DICOM currently supports the following compression schemes, which are
expressed in DICOM as "transfer syntaxes"
- JPEG baseline (lossy 8 bits/pixel) - this is what most people understand
as JPEG
- JPEG extended sequential with 8 or 12 bits/pixel, lossy
- JPEG lossless with 2-16 bits/pixel
- JPEG 2000 (Part 1) lossy and lossless
- JPEG-LS, which is a fast lossless algorithm based on HP's LOCO-I.
- RLE (run length encoding) as defined in TIFF PackBits
- ZLIB (deflate) encoding for the complete dataset (not only the pixel
data), lossless of course.

Discussion about adopting a variant of MPEG in DICOM has been going on for
years, but so far nothing has been standardised. I believe the Visible
Light working group is chewing on this issue currently, and my impression is
that they will probably settle for an MPEG 2 process similar to that used on
DVDs. Obvious use cases would be archival of OR videos, endoscopy and the
like.

Regards,
Marco Eichelberg

[drsbhat...@gmail.com]

Hi Marco
You wrote very well explaining the DICOM vs JPEG

I've a doubt- Is DICOM simply JPEG + Metadata built into it?

It looks to me that JPEG images can also be used for medical image transfer/ view and should be an easy way out to implement.

Am I wrong?