RadiAnt DICOM Viewer - Discussion Forum
Adjust Image Window - Negative

Jan 11, 2020 10:26 AM
by DrPaul
Hi,

From my understanding, dicom images are displayed to the screen using the following logic:

ModalityValue = RescaleSlope * StoredValue + RescaleIntercept

n = number of output gray levels (usually 256 or 1024)
w = WindowWidth - 1.0
c = WindowCenter - 0.5

if (ModalityValue <= c - 0.5*w), then WindowedValue = 0
else if (ModalityValue > c + 0.5*w), then WindowedValue = n - 1
else WindowedValue = ((ModalityValue - c)/w + 0.5) * (n - 1)

I know that changing the image window (for e.g., from abdomen to angio) changes the WindowWidth and WindowCenter values to produce the right image. How is negative mode (by pressing F11) produced in RadiAnt? I have tried multiplying StoredValue and ModalityValue by -1, but that does not work in all cases.
Jan 11, 2020 04:51 PM
by RadiAnt
NegativeValue = n - 1 - WindowedValue
Jan 11, 2020 05:13 PM
by DrPaul
Got it right! Thank you :)
Post reply
Author (first name or pseudonym):

Message:

You have to accept cookies to be able to post messages.
Visitors can post messages on the forum without having to register. Please input your first name or pseudonym in the "Author" field. Do not publish any personally identifiable information (PII).

Please ensure you write your posts in English so that our international audience can understand and reply to your message.

The Administrator reserves the right to remove any messages that violate our forum rules; for example, those that are not related to the RadiAnt DICOM Viewer software, published in a language other than English, contravene regulations, etc.