How to transfer graph data into MATLAB using image processing?

6 次查看（过去 30 天）

显示更早的评论

Sam 2019-2-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/446778-how-to-transfer-graph-data-into-matlab-using-image-processing

回答： Image Analyst 2019-2-26

回答（2 个）

Asad Mirza 2019-2-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/446778-how-to-transfer-graph-data-into-matlab-using-image-processing#answer_362546

What you need is is either GRABIT or WebPlotDigitizer.

5 个评论
显示 3更早的评论隐藏 3更早的评论

Sam 2019-2-26

Hi, can suggest a solution to filter the vertical and horizontal line?

Asad Mirza 2019-2-26

编辑：Asad Mirza 2019-2-26

在 MATLAB Online 中打开

Easiest way is find the gradient of the image and then set a threshold value to what counts as a verticle line. But it's a quick and dirty way and prone to errors.

im=imread('image.jpeg');
im=rgb2gray(im);
[gx gy]=imgradientxy(im); 
Verts=gx>800; %% gx for verticle lines or gy for horizontal lines
imshow(Verts);

请先登录，再进行评论。

Image Analyst 2019-2-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/446778-how-to-transfer-graph-data-into-matlab-using-image-processing#answer_362722

在 MATLAB Online 中打开

image.png

If it were me, and it was just this one picture (not hundreds of pictures), I'd

bring it into Photoshop
Crop the image to the bounding box
Resize the image to 2100 pixels high.
Enlarge the canvass to 2400 pixels by extending out the bottom
Paint white over all the non-signal parts using the paintbrush tool(this is the only time-consuming part)
Save it out as a PNG image
Bring the image into MATLAB and scan the image column by column looking for the last black pixel

I'm attaching a rough estimate of what I get through Step 6. Of course this is a very very low resolution image so it's very difficult to determine what is signal and what is grid or numbers. It's essentially a judgment call so that's why I chose to do pre-processing manually in Photoshop.

For Step 7:

for col = 1 : columns
    rowOfSignal(col) = find(grayImage(:, col) < 128, 1, 'last');
end
% Convert to range 300 - 2400
signalValue = 2400 - rowOfSignal;