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UPDATE

I could manage to take a "decent" photo of what I'm refering to with the LED's: enter image description here

Is that caused by the printer? This is how the LED's are drawn:

\documentclass[a4paper,12pt]{article}

\usepackage[a4paper, margin=2cm]{geometry}
\usepackage[utf8]{inputenc}
\usepackage[]{circuitikz}

\begin{document}
    \begin{circuitikz}
        \draw[color=blue] (0,0) -- (2,0)node[fulllediodeshape,scale=0.7,color=black](q0){}; 
    \end{circuitikz}
\end{document}

ORIGINAL

I'm printing on paper a circuit that has multiple elements with color, and some of them seem to appear with two kind of colors one darker than the other. Here for example you see a node (circ node) that has like an outer ring of darker color than the center:

enter image description here

Is this caused by the printer?

ElSabio
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  • In my opinion, since the picture contains colored part, the black color is being produced by mixing all 3 colors (CMY) instead of a pure black color (K). So, the black part can be not too black. – Sigur Jan 07 '20 at 22:25
  • Yeah but I also have some LED's all black without any other color nearby and they show up the same, with a line of darker black around a greyish area inside the LED. I cannot show them because the scanner's light is so powerfull that it appears black instead of gray. – ElSabio Jan 07 '20 at 22:29
  • You can look at the PDF with high magnification and see if the problem is the printer or not. Keep in mind that antialiasing algorithms can kick in and create intermediate colores on sharp, not horizontal or vertical lines --- that's normal and good. See https://www.geeksforgeeks.org/anti-aliased-line-xiaolin-wus-algorithm/ – Rmano Jan 08 '20 at 08:41
  • In the case you show, that could be the printer or even the scanner --- it is not possible to have perfect alignment between the several colors. – Rmano Jan 08 '20 at 08:42
  • Your updated picture and code doesn't correspond (for example, shorter and thicker arrow in the picture than the arrow produced by the code). – quark67 Jan 08 '20 at 17:46
  • Yeah that code does not provide the photo drawing, but it is part of it. It is how they were drawn in the whole circuit. – ElSabio Jan 08 '20 at 17:56
  • In your picture, is the black text, if any, printed gray or black? Can you test without colored wires? Can you test on another printer (not the same brand)? I don't own a color printer but I known that some printers, to produce a darker black, overlap black ink with cyan, magenta and yellow ink. But if this is the case, why only the border of the triangle of the LED, and not the interior? Opened with a vector design software, the triangle of the LED in the resulted PDF has a pure black stroke and a pure black fill. Strange that the printer uses two different level of black. – quark67 Jan 08 '20 at 18:25
  • Oh, yes you are right, the text an everyother thing in the circuit is grayish instead of black. Except the borders of the LEDs and "black" nodes. What is happening? To be clear, in the PDF is all black, no gray fuss. – ElSabio Jan 08 '20 at 18:35
  • I think that black text is printed in the graycolor space (that uses only the black ink), and the graphic (which has colored wires) is printed in cmyk color space and the latter uses cyan, magenta, yellow and black ink to produce the black color. This need a confirmation, but you can read the rich black Wikipedia article about this. Perhaps add cmyk, color-profile and pdf tags in the question for more attention. Also read this: https://tex.stackexchange.com/q/75451/132405 – quark67 Jan 08 '20 at 19:19
  • Can you test with adding \usepackage[cmyk]{xcolor} and \definecolor{myblack}{cmyk}{1 1 1 1} in your preamble, before \usepackage[]{circuitikz} and draw your LED with the myblack color instead of black? – quark67 Jan 08 '20 at 19:29
  • My guess is this is magic that your printer driver and/or printer does. The only way I have found to get exactly the colours I want for diagrams is to print CMYK PostScript to a PostScript colour laser printer using its PostScript driver. In this case, I can get exactly the colours (by number) that I specify. (Or if you have a colour laser that accepts PDF, send a CMYK PDF directly to the printer. I have found that some PDF driver workflows (e.g., the CUPS one) convert my PDFs to RGB along the way and colours are stuffed up. If you have an inkjet, you're at the mercy of the driver. – David Purton Jan 08 '20 at 23:52
  • FWIW, the PDF produced has RGB blue and Grayscale Black. This doesn't explain why you get a different colour for the stroke as to the fill. But there is a chance you will get more consistent output if you use either \useackage[rgb]{xcolor} or (as @quark67 suggested) \usepackage[cmyk]{xcolor}. In theory you shouldn't need to redefine your black colour in either case, but you never know. – David Purton Jan 08 '20 at 23:55

1 Answers1

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It is the printer.

I did another try in a different copy centre and it is perfect now:

enter image description here

Thank you all for your comments.

ElSabio
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