I am working on ultrasound images, and I have access to both DICOM and raw DICOM. I would like to know what the difference between the two is especially speaking of resolution and the size of the images, the nature of the information contained, acquisition. Moreover, I am very much interested in understanding what sort of processing those images undergo before being extracted in DICOM/raw DICOM format in order to figure out the post-processing necessary before moving on with the image analysis for my own research goals.
If you upload an example of the same image in raw and non-raw, I could find out.
'Raw images' usually are pixel-data only. I never heard of 'raw dicom', and it might well be that 'raw dicom' is vendor specific.
"Raw DICOM" exists in digital radiography/mammography, don't know about ultrasound. "Raw" ("for processing") is only corrected for defective pixels and flatness of the image, while "non-raw" ("for presentation") are processed to look similarly to traditional images (on radiographic film). E.g. in raw images pixel values may be linearly proportional to radiation dose, in non-raw not neccessarily. And both are DICOM! But once more, this is about radiography/mammography, don't know about ultrasound.
Raw DICOM is present in GE Cardiac Ultrasound machines, it's usually used to evaluate Strain using 2 or 3D speckle tracking in propietary software (EchoPac). Non raw images cannot be used to evaluate Strain using 2 or 3D speckle tracking.
For Toshiba ultrasound imaging systems, but I think it can be generalized to other ultrasound imaging system, RAW DICOM corresponds to data on which fewer display processing have been applied.
More precisely, RAW DICOM are encoded on 12bits without compression, whereas "classic" DICOM images are generally screenshots encoded on 8bits with jpeg lossy compression. Moreover, RAW DICOM are not saturated for high values and not subject to tresholding for low values. For your question about the sizes, the (physical) size of the pixels in not the same in the two formats but I could not give you more details.
Generally, RAW DICOM are proprietary formats that require the use of proprietary softwares to be analyzed, because the DICOM field containing image information is encrypted.
An article that compares the two in more details:
Echo-power estimation from log-compressed video data in dynamic contrast-enhanced ultrasound imaging. Payen T, Coron A, et al. Ultrasound in medicine and Bio 2013
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