brain images: Change data type of brain image

1 min read

Last update: 2012/09/04

An image file can be saved in different formats such as uint8 or int16, etc, based on different number of bytes used for each voxel. How to convert between them? Here is one solution using SPM functions (no need SPM’s interface). Assume img1.img is the original image with datatype int16, img2.img is the file you want to create with datatype uint8.

V=spm_vol('img1.img');
disp(V.dim); %you will find the last element is 4 in SPM2
V2=V;
V2.fname='img2.img';
V2.dim(4)=2;
M=spm_read_vols(V);
spm_write_vol(V2, M);

Explanation:
Variable V.dim is a 1×4 vector. The first three are number of voxels (or dimensions) along x,y and z direction. The last element (4th) is the number of bytes used for each voxel and it is this variable we want to change.

Note: If you are using SPM5 or SPM8, then the data type information is in V.dt

V=spm_vol('img1.img');
disp(V.dt); %for SPM5 and SPM8
V2=V;
V2.fname='img2.img';
V2.dt=[2 0];
M=spm_read_vols(V);
spm_write_vol(V2, M);

I myself find the following 3 SPM functions are extremely useful and use them a lot:

V=spm_vol('img1.img'); % read header information of an image file
M=spm_read_vols(V); % read the data (voxel intensity) from an image. The result is a 3D matrix with each point corresponding to a point in brain.
spm_write_vol(V2, M); % write data to an image file.

Check out here to see how to convert images with different formats (e.g. ANALYZE, Nifti, DICOM etc)



写作助手,把中式英语变成专业英文


Want to receive new post notification? 有新文章通知我

第五十期fNIRS Journal Club通知2024/03/30, 10am 王一晖

早期的 STEM 教育对于以后的学习至关重要。现有研究尚未就STEM教学法达成共识,学生先验知识对基于故事的STEM教学法的影响还有待探讨。来自澳门大学张娟教授团队的王一晖将会分享基于fNIRS超扫描
Wanling Zhu
9 sec read

第四十九期fNIRS Journal Club视频 高倩博士

Youtube: https://youtu.be/a2QlCFZUytA优酷: https://v.youku.com/v_show/id_XNjM3MjMyNjUxMg==.html 竞技比赛中,
Wanling Zhu
12 sec read

第四十九期fNIRS Journal Club通知2024/02/24, 10am 高倩博士

竞技比赛中,特别是需要注意高度集中的射击项目中,如何保持稳定的注意控制对运动员的表现至关重要。近期的一项研究调查了赛前短时正念练习是否对运动员在射击比赛中的注意控制具有提升作用。来自北京体育大学心理学
Wanling Zhu
9 sec read

2 Replies to “brain images: Change data type of brain image”

  1. If I’m not mistaken that’s only true for SPM2. For SPM5 and SPM8 the field ‘dim’ has only three entries and the first entry of the field ‘dt’ carries the information about the data type.

Leave a Reply

Your email address will not be published. Required fields are marked *