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.NET Forum / Windows Forms / WinForm General / January 2007Non-proportional (non Rectangular) resizing
Hi all... I have developed an application for managing a very large resource of artist's paintings and posts them to a web site. The application works well. I'm trying to reduce the complexity of having to work with photoshop and integrate one feature into the application > Distortion Transformations. Background Information: When paintings are photographed, it's impossible to get a completely perfect image that requires straightening prior to cropping for a number of rasons - the photographer is not standing square on to the painting, the painting is leaning, the camera is not at the correct height, the camera causes barrel distortion, etc... Therefore each image must be loaded into photoshop, all 4 corners selected using the polygonal lasso tool then manually applying a Distort Transformation (Edit > Transform > Distort) on the selected region. The Problem: The GDI library comes standard with several rectangular transformations - stretch, Skew, etc.. But these apply only to a perfect rectangular region where all points are perpendicular to each other. I have no problems in selecting the non-rectangular region - this is easy. I'm stumped at trying to work out how to take this region and applying the Photoshop like Distort Transformation. Anyone have any pointers? Thanks in advance... Graeme Transformations are all done using Matrix math. This is not going to be an easy task, because you will have to understand Matrix math to do it. Here are some articles and sample code to get you started: http://www.bobpowell.net/transformations.htm http://www.codeproject.com/csharp/matrix_transformation.asp http://www.euclideanspace.com/maths/algebra/matrix/arithmetic/index.htm http://www.euclideanspace.com/maths/algebra/matrix/code/sftranslation_csharp.htm  SignatureHTH, Kevin Spencer Microsoft MVP Software Composer http://unclechutney.blogspot.com The shortest distance between 2 points is a curve. > Hi all... > [quoted text clipped - 35 lines] > > Graeme Hi... Thanks for your suggestions - I've had a look at all the links mentioned. Bob's and the CodeProject artile I've already looked at both and they deal with rectangular regions (simple transformation) and not 4-point polygons (complex transformation). I've also looked at Gimp and Paint.Net - both only deal with regions (simple transformation) and don't have Photoshop's distort transformation (complex transformation). I'm trying to do 4-point polygons (complex transformation) and not rectangular regions (simple transformation). The GDI+ matrix transformations only handle rectangular regions (simple transformation) as far as I can ascertain. To clarify what I'm trying to do, I'll give you another example - can send you a sample image if you think that you know how it's done. Example: The bottom-left and top-right corners are not squared to the Top-left & bottom-right corners. To square the image, the top-left and bottom-right must stay anchored whilst the bottom-left must be distorted towards the top and the top-right corner must be distorted to the right. Be aware that no two photos are the same and each photo will require different distort transformation adjustments. Do you still think that your suggestion will work or do you have another idea? Thanks for your help in advance, Graeme > Transformations are all done using Matrix math. This is not going to be an > easy task, because you will have to understand Matrix math to do it. Here [quoted text clipped - 47 lines] >> >> Graeme Yes, I have a good understanding of what you're trying to do. The Bob Powell and CodeProject references were just for the purpose of general information about Matrices. The other 2 references are more specific, one of which goes well into the mathematics, and one of which provides some samples of C# Matrix math algorithms, although you will still have to create your own matrices to do the work. But it WILL involve using Matrix transformation, and you will have to figure out the Math. SignatureHTH, Kevin Spencer Microsoft MVP Software Composer http://unclechutney.blogspot.com The shortest distance between 2 points is a curve. > Hi... > [quoted text clipped - 83 lines] >>> >>> Graeme Thanks for the quick response Kevin. I've had a good look at GDI+ and Matricies through alot of hand coding and all I get are simple transformations. I fail to see how GDI+ can handle complex transformations other than rectangular regions. Kind Regards, Graeme > Yes, I have a good understanding of what you're trying to do. The Bob > Powell and CodeProject references were just for the purpose of general [quoted text clipped - 93 lines] >>>> >>>> Graeme My point was not about GDI+ as such, but that you need to use Matrix math to do your transform. In fact, the DirectX library has a matrix class that has quite a bit of functionality built in, and is completely configurable, which may be useful to you, or provide you with the knowledge you need to do your transform. I might mention that what you need is not an affine transform, which does not provide distortion. What you need to understand is that a matrix provides a vector-based translation method, so what you need to do is an orthagonal transform, to change the angle of the corners of your rectangle. See http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/directx9_m/dire ctx/ref/ns/microsoft.directx/s/matrix/matrix.asp. SignatureHTH, Kevin Spencer Microsoft MVP Software Composer http://unclechutney.blogspot.com The shortest distance between 2 points is a curve. > Thanks for the quick response Kevin. > [quoted text clipped - 103 lines] >>>>> >>>>> Graeme Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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