Ah, sorry-- that would be while opening the artwork in any viewing software which I have owned. Any version of MS fax/image viwer, PS, In-Des, GifView, Ifran, Micrografix, Office, and so on... many types of software. However, here are some images for examination. The first image [test-drawing_original] is a save of the original PSD drawing (e.g. one layer) from PS as a JPG rgb-8, 600 dpi, 1 px lines. This is the same intensity as seen in any viewing software, and also as the image prints (on many platofrms, but let's leave the bewildering world of printing aside for now!). Next image [screen-Capture] is a screen capture of PS on my laptop showing the extra layer 'trick'. Zoom = 100%. Here there are two copies of the original layer, both using Multiply blend mode. I hope you can see that the lines on my screen are much darker and more "saturated", if that is the correct term, than the single layer alone. The last image [test-drawing_layers] shows a jpg save to rgb-8 from the PSD with these extra multiply layers enabled. The resulting line artwork is darker than the original (one layer) drawing, but not as dark as in the 3-layer PSD while looking at PS. I hope these jpgs appear for you as they do on my various computers.
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