Find weight of all lines/drawings

Question

I need to know if it's possible to find the weight (diameter) of all lines/drawings in a psd file.

Since silk screen printing dosen't allow me to print smaller lines/paths/drawings than 0,6mm i need a preview to see waht would't be printed.

Answer 1

Building on Krzysztof Kosiński answer, one can use morphology operators to solve this. Here is how you do it in Photoshop.

Image 1: Example of using morphology to find all less than 2 pixel wide areas. Too thin areas in red (image on right). Image of otter from Deviantart (CC-BY).

Procedure

1. Select the black pixels in your image. (using channels or selective color)
2. Contract (Select → Modify → Contract) selection by half (1/2) as many pixels as you want to be the cutoff.

image 2: Contract selection

3. Expand (Select → Modify → Expand) by same number (or slightly more)
4. fill a layer with this selection so that you can compare

Image 3: After some curve and layer adjustment so that the error is easily visible.

Answer 2

It should be possible to estimate the effect of this kind of limited resolution even for raster images by applying a morphological operation known as opening, which is equivalent to erosion followed by dilation.

https://en.wikipedia.org/wiki/Opening_%28morphology%29

This is available as a plugin for GIMP, and I'm sure it's also available for Photoshop somewhere. You only need to know how many pixels will correspond to 0.6mm, to pick the correct size for the structuring element.

Alternatively, you can try completely rasterizing the image and then resizing it so that one pixel corresponds to 0.6mm. You'll have to experiment and see which method gives a result which is more similar to what you see coming out of the printer.

Answer 3

There's no easy way to do this without vectorized lines (which have a stroke in points that you could convert to mm). If it is vector you can just enlarge the image or increase stroke sizes.

You can use Photoshop's ruler tool (quick key 'I' in the eye dropper tool palette button) to determine the pixel size or size in millimeters and see if the artwork elements are wide enough to show up, but this isn't really likely to give an accurate idea of how the screen-printed image will look since it will depend on your process and the mesh of your screen.

If possible just try a test screen-print and if the lines aren't showing up adjust the artwork accordingly.