Using VIPs library and Lua to process pictures

[hzm199822]

To get an original picture from the file, what I want to do is to select a position, cut a rectangle, and make a concave or convex semicircle on the edge of the rectangle, and make this area transparent. Is there an appropriate API or solution?

[jcupitt]

Hi @hzm199822, could you post a sample image showing what you want?

[jcupitt]

For example, this:

#!/usr/bin/luajit

local vips = require "vips"

local im = vips.Image.new_from_file(arg[1], {access = "sequential"})

-- make a transparent square ... just RGBA all 0 (black)
local square = vips.Image.black(64, 64, {bands = 4})

-- insert into the main image
im = im:insert(square, 100, 100)

im:write_to_file(arg[2])

makes a square in an image transparent, eg.:

$ ./try320.lua ~/pics/lion.png x.png

Where do you need the semicircle? Do you need a line, or a segment?

[hzm199822]

[hzm199822]

What I want is not all white, but translucency. Or that piece becomes a watermark

[hzm199822]

What I want is that this square is just a benchmark. I want to add a semicircle or subtract a semicircle on any two sides of the four sides of the square. Of course, the diameter of the semicircle must be smaller than the side length

[hzm199822]

What I want is that this square is just a benchmark. I want to add a semicircle or subtract a semicircle on any three sides of the four sides of the square. Of course, the diameter of the semicircle must be smaller than the side length.
The translucency on the right side of the image can also be a fuzzy watermark. Then the block on the left side, I hope, is the same as the missing block in the original image, which is equivalent to providing a picture. I need to make two images, one is with watermark, the other is a small piece taken out separately
I don't know if luavips can do this for images (add or subtract semicircles on the edges of rectangles)

[jcupitt]

The square in the lion only looks white because the page background is white. Try opening the image in a new tab.

You can overlay complex shapes with composite. You give it an RGBA image, one of the PDF blending modes (eg. over) and a position.

Could you upload some test images? It would save me making them. Just drag the images into the text box.

[hzm199822]

huangzhiming zm.huang@ucloud.cn 签名由 网易邮箱大师 定制 On 11/4/2020 15:58，John Cupitt<notifications@github.com> wrote： The square in the lion only looks white because the page background is white. Try opening the image in a new tab. You can overlay complex shapes with composite. You give it an RGBA image and one of the PDF blending modes (eg. over) and a position. Could you upload some test images? It would save me making them. Just drag the images into the text box. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

[jcupitt]

Composite example:

#!/usr/bin/luajit

vips = require 'vips'

local image = vips.Image.new_from_file(arg[1], {access = "sequential"})
local overlay = vips.Image.new_from_file(arg[2], {access = "sequential"})

-- composite the overlay at 50, 20 using 'over' blend mode
image = image:composite(overlay, "over", {x = 50, y = 20})

image:write_to_file(arg[3])

Generates:

[hzm199822]

I mainly want to extract a figure from the original image, then save it, and change the extracted part of the original image into translucent or other

[hzm199822]

It's important to extract this step, but it seems to me that the API can only extract simple rectangles

[jcupitt]

You can apply masks if you want more complex shapes.

Post a set of sample images and I'll have a go.

[hzm199822]

like this? huangzhiming zm.huang@ucloud.cn 签名由 网易邮箱大师 定制 On 11/4/2020 17:07，John Cupitt<notifications@github.com> wrote： You can apply masks if you want more complex shapes. Post a set of sample images and I'll have a go. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

[jcupitt]

Use the github website and drag images into the text box.

[hzm199822]