3 7. APPENDIX A: IMAGE THUMBNAILS ADDED TO DICOM IMAGES
7 PathSpeedâ"¢ PACS will create a thumbnail for each DICOM Image SOP Instance of
8 the following Photometric Interpretation values:
13 The thumbnail is derived from the original pixel data by downscaling the image
14 size to 128 Ã- 128 pixels or less, and added to the original SOP Instance
15 with a private sequence data element in the DICOM Image SOP Instance.
17 One thumbnail is created per DICOM image. For a multi-frame image,
18 only one thumbnail is created from the center frame.
19 The number of the frame, which is used for the thumbnail creation is included in
20 the Image SOP Instance (see Section 7.3).
21 In PathSpeedâ"¢ PACS, the thumbnails are used by the PathSpeedâ"¢ Web
22 display application for image navigation when browsing through a set of images.
23 With the information published in this Appendix, a DICOM application receiving
24 the images from PathSpeedâ"¢ PACS can also explore the thumbnail data
25 encoded in the Image SOP Instances.
27 7.2 IMAGE THUMBNAIL COMPRESSION
29 The thumbnail is compressed with 8 bits or 12 bits JPEG lossy compression
30 format, depending on the stored pixel depth of the original images.
31 For all Image SOP Instances with bits stored equal to or less then 8,
32 the thumbnail image is stored one
33 byte per pixel and compressed by JPEG 8-bits lossy compression.
34 For all Image SOP Instances with bits stored equal to or less 12,
35 the thumbnail image is stored two bytes per pixel and compressed
36 by JPEG 12-bits lossy compression.
37 For all Image SOP Instances with bits stored greater than 12, the pixel data of
38 the thumbnail image id first shifted to fit into the 12 bits scope and then
39 stored two bytes per pixel
40 The thumbnail is compressed by JPEG 12-bits lossy compression.
41 The bits shifted is saved in the GE Private Image Thumbnail Sequence,
42 as specified in the next section.
43 All thumbnails are represented in the unsigned format (either byte or two-bytes
45 If an Image SOP Instance contains a signed pixel data element, the thumbnail
46 pixel data will be offset to the unsigned scope.
47 The offset added is saved in the GE Private Image Thumbnail Sequence,
48 as specified in the next section.
52 7.3 IMAGE THUMBNAIL ENCODING
54 PathSpeedâ"¢ PACS adds a private sequence data element (GE Private Image
55 Thumbnail Sequence) to an Image SOP Instance for the thumbnail encoding.
56 There is no any change to the existing data attributes of the SOP Instance.
57 The GE Private Image Thumbnail Sequence is specified in the following table.
62 Private Creator ID (0009,00xx) LO 1 GEIIS, Reserve xx00-xxFF of group 0009
64 GE Private Image Thumbnail Sequence (0009,xx10) SQ 1 Always only one item
67 > Sample per Pixel (0028,0002) US 1 Copy from the original SOP Instance
68 > Photometric Interpretation (0028,0004) CS 1 Thumbnail Photometric
73 > Planar Configuration (0028,0006) US 1 Thumbnail Planar Configuration.
75 > Number of Frames (0028,0008) IS 1 Copy from the original SOP Instance.
76 The thumbnail itself is always single frame.
77 > Rows (0028,0010) US 1 Thumbnail Rows of Image Matrix, ≤ 128.
78 > Columns (0028,0011) US 1 Thumbnail Columns of Image Matrix, ≤ 128.
79 > Bits Allocated (0028,0100) US 1 Copy from the original SOP Instance
80 > Bits Stored (0028,0101) US 1 Copy from the original SOP Instance.
81 If this value is 8 or less, the thumbnail JPEG stream is 8 bits compressed,
82 otherwise, it is 12 bits compressed.
83 > High Bit (0028,0102) US 1 Copy from the original SOP Instance
84 > Pixel Representation (0028,0103) US 1 Copy from the original SOP Instance
85 > Largest Image Pixel Value (0028,0107) US/ SS 1 Copy from the original
87 > Pixel Padding Value (0028,0120) US/ SS 1 Copy from the original
89 > Window Center (0028,1050) DS 1-n Copy from the original SOP Instance
93 > Window Level (0028,1051) DS 1-n Copy from the original SOP Instance
94 > Rescale Intercept (0028,1052) DS 1 Copy from the original SOP Instance
95 > Rescale Slope (0028,1053) DS 1 Copy from the original SOP Instance
96 > Private Creator ID (0029,0010) LO 1 â€"GEIIS“, Reserve 1000-10FF
97 of group 0029 in this item.
98 > Shift Count (0029,1010) UL 1 Number of bits pixel values were shifted down
99 to get them into the 12 bits range before JPEG compression.
100 > Offset (0029,1012) UL 1 Value added to pixel values to convert them from
101 signed to unsigned values before JPEG compression.
102 > Actual Frame Number (0029,1014) UL 1 Actual frame number of image the
103 thumbnail was generated from. For multi-frame images, this should represent
104 the center frame. Only one thumbnail is created for the entire
106 > Private Creator ID (7FD1,0010) LO 1 â€"GEIIS“, Reserve 1000-10FF of
107 group 7FD1 in this item.
108 > GE IIS Compression Type (7FD1,1010) UL 1 PathSpeedâ"¢ PACS internally used
109 data compression code. Always 26 for thumbnail
110 > Pixel Data (7FE0,0010) OB 1 8 bits or 12 bits JPEG lossy compressed thumbnail
111 image pixel data stream.
114 7-1: SPECIFICATION OF GE PRIVATE IMAGE THUMBNAIL SEQUENCE
116 The GE Private Image Thumbnail Sequence includes a number of standard data
117 elements directly copied from the original Image SOP Instance,
118 to which the sequence is added.
119 These data elements are marked as Copy from the original SOP Instance in
121 These data elements provide the original pixel data context from that
122 the thumbnail has been derived. Note that they do not contain the values
123 specific to the thumbnail.
124 The GE Private Image Thumbnail Sequence uses a number of standard data elements
125 to describe the properties of the thumbnail pixel data.
126 Note that these data elements in this sequence really contain the values
127 specific to the thumbnail, but not to the original image pixel data