Image display having automatic image adjustment

• US 4,975,970 A
• Filed: 04/07/1989
• Issued: 12/04/1990
• Est. Priority Date: 03/18/1987
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Sievenpiper, Crispian L., Zettel, Hubert A.
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US07/336,605
• Time in Patent Office: 606 Days
• Field of Search: 382/6, 382/18, 382/47, 382/51, 358/80, 364/414
• US Class Current: 382/131
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/10116 X-ray image
• CPC Class Codes: G06T 2207/20021 Dividing image into blocks, subimages or windows
• CPC Class Codes: G06T 2207/30004 Biomedical image processing
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• CPC Class Codes: G09G 1/00 Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of datacathode-ray oscilloscopes G01R13/20; radar display arrangements G01S7/04; display of digital non-picture data in television systems H04N7/0255
• CPC Class Codes: H05G 1/60 Circuit arrangements for obtaining a series of X-ray photographs or for X-ray cinematography

Abstract

A graphical image display provides improved image presentation due to potential removal of background data which would otherwise degrade presentation of the region of interest and due to automatic adjustment of image brightness and contrast based on operator preference. Statistical analysis of the image data is employed. The invention is particularly useful in medical diagnostic imaging.

Claims

1. Apparatus for displaying images from image data employing a preset image scale factor, comprising:

display means for displaying an image;

data means for supplying said image data;

setting means coupled to said display means and to said data means for allowing an operator to modify chosen image characteristics of a first displayed image having arbitrary characteristics;

computing means responsive to said setting means for finding said scale factor for applying to statistical attributes of image data corresponding to said first displayed image in order to generate a modified image having said chosen characteristics; and

scaling means coupled to said computing means and to said data means for scaling said statistical attributes of image data corresponding to subsequently displayed images by said scale factor.

2. The apparatus of claim 1 further comprising histogram means coupled to said computing means and to said scaling means for storing a histogram of the image data corresponding to a respective image, said statistical attributes being derived from said histogram.

3. The apparatus of claim 1 employing two scale factors wherein said chosen display characteristics are brightness and contrast, said computing means finding a brightness scale factor proportional to the difference between the mean brightness of said modified image having said chosen characteristics and the mean brightness of said image data corresponding to said first displayed image, said computing means finding a contrast scale factor proportional to the ratio of mean brightness of pixels in said image having said chosen characteristics to the standard deviation from mean brightness of pixels in said image data corresponding to said first displayed image.

4. The apparatus of claim 2 further comprising background removal means coupled to said histogram means for selectably causing image data below a calculated level in said histogram to be ignored in displaying an image, said calculated value corresponding to the first valley immediately following the first peak in said histogram.

5. Apparatus for displaying medical diagnostic images from image data, comprising:

display means for displaying an image;

data means for supplying said image data, said image data including an image histogram and the field of view of said image; and

background removal means coupled to said data means for causing image data below a calculated level in said histogram to be ignored in displaying an image if said field of view is below a predetermined size, and for otherwise using said data below said calculated level in displaying an image, said calculated level corresponding to the first valley immediately following the first peak in said histogram.

6. The apparatus of claim 5 wherein said image data includes results from NMR measurements, wherein said image data further includes an indication of the type of coil used in deriving said NMR measurements and wherein the predetermined size of field of view is dependent on the RF coil indicated.

7. A method for adjusting brightness and contrast of images constructed from image data including a plurality of pixel values for each respective image, said method comprising the steps of:

displaying a first image corresponding to at least a portion of said image data with arbitrary initial brightness and contrast;

adjusting the appearance of said first displayed image to provide an operator-preferred image;

computing a brightness scale factor derived from the difference between the mean brightness of said preferred image and the mean brightness of the pixel values corresponding to said first image;

computing a contrast scale factor derived from the ratio of mean brightness in said preferred image to the standard deviation from mean brightness of said pixel values corresponding to said first image; and

changing the mean brightness and standard deviation of subsequently displayed images according to said brightness scale factor and said contrast scale factor.

8. The method of claim 7 further comprising the step of:

providing a histogram of said image data corresponding to each respective image, said histogram representing the number of pixels of an image having each possible pixel value.

9. The method of claim 8 further comprising the step of:

deleting from said histogram data corresponding to pixel values below a level representing background portions of a respective image.

10. The method of claim 9 wherein said level is found by a method comprising the steps of:

finding the lowest histogram bin value x such that the number of pixels in the histogram bin x, designated L_x, satisfies the relation L_x-1 <

L_x >

L_x+1 ; and

finding the first bin value y while increasing in said histogram from x such that the number of pixels in the histogram bin y, designated L_y, satisfies the relation L_y-2 L_y-1 L_y L_y+1, said level being equal to y.

11. A method for displaying medical diagnostic images constructed from image data corresponding to each respective image, said image data obtained from NMR measurements and including an indication of the type of RF coil used in obtaining said measurements, said image data further including a histogram and an indication of size of field of view corresponding to each image, said method comprising the steps of:

determining whether said size of field of view is below a predetermined size dependent on said indicated RF coil; and

deleting from said histogram data corresponding to pixels representing background portions of a respective image if said field of view is below said predetermined size.