Answers.Body: <p>The cause is simple. The images are authored in a vector or CAD format. When Lego rendered these vector images to the low resolution images in the PDFs, the thin outlines got turned into lines with a thickness of one pixel. Due to their small yet complex cross-section the axles get mostly covered by their outlines.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-07-21T22:10:13.380Z
Answers.LastActivityDate: 2020-07-21T22:10:13.380Z
Answers.UserDisplayName: Anonymous
Answers.Body: <p>I don't have this set, but used <a href="https://brickset.com/sets/8421-1/Mobile-Crane" rel="noreferrer">8421</a> as a test. This set is also released in 2005.</p>
  <p>Looking at the <a href="https://www.lego.com/biassets/bi/4505210.pdf" rel="noreferrer">PDF</a> you see the same color scheme of the axles, were the black appear to be gray and vice versa</p>
  <p><a href="https://i.sstatic.net/q0e06.jpg" rel="noreferrer"><img src="https://i.sstatic.net/q0e06.jpg" alt="enter image description here" /></a></p>
  <p>When looking at the instruction manual</p>
  <p><a href="https://i.sstatic.net/dTcWM.jpg" rel="noreferrer"><img src="https://i.sstatic.net/dTcWM.jpg" alt="enter image description here" /></a></p>
  <p>You see the normal colors, so indeed your set came with the normal colors and due to some bad scanning and compression the pdf got discolored</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-07-21T16:34:56.663Z
Answers.Text: Lego's instruction manuals have shockingly bad colour fidelity. This is improved in recent years with the black parts being outlined in white, which explains those axles. But PDF versions of the instructions have always been at best as bad as printed instructions, and are often worse, when it comes to colour quality. Why this is, is a mystery.
Answers.UserDisplayName: Mr. Shiny and New 安宇
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-07-21T09:59:02.220Z
Answers.LastActivityDate: 2020-07-21T09:59:02.220Z
Answers.UserDisplayName: Joost
Body: <p>I've been looking through the parts of an <a href="https://www.lego.com/cdn/product-assets/product.bi.core.pdf/4280174.pdf" rel="noreferrer">old manual</a> I have and I noticed the odd-length gray axles appear black and the even-length black axles appear white and black.</p>
  <p><a href="https://i.sstatic.net/eVqsp.png" rel="noreferrer"><img src="https://i.sstatic.net/eVqsp.png" alt="axles" /></a></p>
  <p>Is this just an artifact of the lossy compression and thick outline colors? It appears gray parts are outlined in black and black parts are outlined in white. I'm pretty sure this set came with standard axle colors.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-07-21T02:56:54.610Z
Comments.Text: I think you are correct, it look like a crap job of rendering the image in a PDF file.
Comments.UserDisplayName: Dan1138
Tags: <part-identification><technic><instructions>
Title: Why do gray axles appear black and black axles appear white and black in this manual?
UserDisplayName: qwr
ThreadText: # Why do gray axles appear black and black axles appear white and black in this manual?
  
  (Asked by: username_0 on 2020-07-21)
  
  I've been looking through the parts of an [old manual](https://www.lego.com/cdn/product-assets/product.bi.core.pdf/4280174.pdf) I have and I noticed the odd-length gray axles appear black and the even-length black axles appear white and black.
  
  [![axles](https://i.sstatic.net/eVqsp.png)](https://i.sstatic.net/eVqsp.png)
  
  Is this just an artifact of the lossy compression and thick outline colors? It appears gray parts are outlined in black and black parts are outlined in white. I'm pretty sure this set came with standard axle colors.
  
  **Tags:** part-identification, technic, instructions
  
  > **Comments:**
  > **username_1**: I think you are correct, it look like a crap job of rendering the image in a PDF file.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_3 on 2020-07-21. Score: 13 | Accepted answer
  
  I don't have this set, but used [8421](https://brickset.com/sets/8421-1/Mobile-Crane) as a test. This set is also released in 2005.
  
  Looking at the [PDF](https://www.lego.com/biassets/bi/4505210.pdf) you see the same color scheme of the axles, were the black appear to be gray and vice versa
  
  [![enter image description here](https://i.sstatic.net/q0e06.jpg)](https://i.sstatic.net/q0e06.jpg)
  
  When looking at the instruction manual
  
  [![enter image description here](https://i.sstatic.net/dTcWM.jpg)](https://i.sstatic.net/dTcWM.jpg)
  
  You see the normal colors, so indeed your set came with the normal colors and due to some bad scanning and compression the pdf got discolored
  
  > **Comments:**
  > **username_4**: Lego's instruction manuals have shockingly bad colour fidelity. This is improved in recent years with the black parts being outlined in white, which explains those axles. But PDF versions of the instructions have always been at best as bad as printed instructions, and are often worse, when it comes to colour quality. Why this is, is a mystery.  
  
  ---
  
  ### Answer by username_2 on 2020-07-21. Score: 10
  
  The cause is simple. The images are authored in a vector or CAD format. When Lego rendered these vector images to the low resolution images in the PDFs, the thin outlines got turned into lines with a thickness of one pixel. Due to their small yet complex cross-section the axles get mostly covered by their outlines.
  
  
  ---
  
  