View Full Version : Tangential and Sagittal

Mustafa Umut Sarac
13-Aug-2014, 06:40
As You are , I am aware of tangential and sagittal contrast - MTF - curves.

And I saw a optical art piece where the artist had put an 45 degree rotated triangles in rows of aligned triangles.I thought if that different alligned triangles gives lots of depth and dimension to the image , may be engineered combination of alignments of lines gives the same relief effect to the picture.

My question , is it possible to separate these lines - sagittal or tangential - from a picture without or with referencing a third variable for example color , tone , noise ?

I thought medical or satellite image processing softwares would have a option but I could not find a software opens regular tiff or jpeg. And I did not see such a button may be writing macro is necessary.

I dont know whether it is impossible or silly but a question in my mind for few months.

Thank you for your time ,

Mustafa Umut Sarac

13-Aug-2014, 08:23
I used to design and program digital filters for research. I never did a saggital/tangential one but it is certainly possible to do a tangental sharpen filter or variations on that.

To get started here are some resources (NIH Image, the sofware I used to work with many years ago): http://rsb.info.nih.gov/nih-image/manual/menus/process.html#filter
More info here: http://www.gamedev.net/page/resources/_/technical/graphics-programming-and-theory/secrets-of-simple-image-filtering-r1994

Mustafa Umut Sarac
13-Aug-2014, 10:33

Thank you for your reply .

Do Leica relief image is a interplay between saggital and tangential lines ?

Could you please write an tangential and saggital contrast change code for that software ? And I downloaded the JAVA Windows 64 bit version and I am not sure I would be able to open regular tiff jpeg images , can you help with that also ?

I read what you linked above but I dont have experience and example with saggital and tangential.

Thank you,


Dan Fromm
13-Aug-2014, 13:36
Mustafa, I don't think the MTF estimates you asked about are what you think.

The sagittal and tangential MTF traces you refer to are estimates (measured or calculated, it makes no difference) along a pair of orthogonal lines in the image plane. They are not lines in the image. The farther apart the traces are, the worse astigmatism is. That's all.