Blips on an Image file inserted in a Drawing

[jR0sal3s]

Our dwg package used rendered images inserted into a sheet of a drawing (idw) as part of the presentation (Manage/Insert Object/Create from File...)

It works fine but in some if not most instances when images are resized to fit into the sheets, blips appears (see attached image).  My research suggest that it may be a cause of small sampling, in 3DS max it can be easily fix by increasing the sampling value.

Anyone knows why this happened in Inventor and how to fix this?...

jR

[-niels-]

Can't say why this happens in Inventor, but I'm going to take a guess that it might be jpg related.
(Assuming you're inserting jpg's)

I'm guessing this because of the compression used for jpg's.
If this is the problem then it might be easy to fix by changing the image to a losless format like png or even bmp.

This is just a wild guess though, I've never seen this occur so i hope this helps.

[jR0sal3s]

i did tried with other files other than jpg but it didnt solve the problem....the images were generated from inventor renderings but theres just no way of controlling the sampling of the image....it is generally limited to the size(px) of the image that can be change only.

Only thing i also have observed is that if this image with blips is being edited, the image that opens shows no blips at all..(.the printed copies also shows those blips)

the only solution i am using now is not to resize as much as possible, when the image is inserted..

[-niels-]

Ok, it's a weird issue though...
Could you post an example or some steps to recreate this?
I would like to see if i can recreate this.

[jR0sal3s]

1. Open an Inventor dwg file (idw).
2. Manage/Insert Object/Create from File/Browse (to attached image)
3. Position the image on the layout and you can see already the blips..
  a. if you double click the image it opens to its pristine image (without blips).
  b. if printed that blips appears as well

the image files were produced by the ff..

1.Tools/Application Options/Colors Tab/Background Image/(bmp image all white)

2. View/Realistic Rendering/

  a. modified Two lights options with 4 lights on, brightness about 40

  b. object shadows activated

  c. used snipping tool to save an image file to jpg or png (snipping was used as it is faster than the File/Export/Image which re-render the image again to save the file)

attachment:

Capture.jpg  (Snipping Tool)

Capture.png (Snipping Tool)

y.png (File/Export/Image )

[-niels-]

Ok, i see the blips on your attached images as well.

I opened the image in photoshop and examined the area where the blips appear and it seems it's mainly the pixels that aren't fully black that become blips.
I tested by coloring the problem zone full black and that made the blips disappear. (image attached)

I'm not sure where the RGB threshold lies exactly, or why near black pixels would turn into these blips but it sure is a weird problem.

I don't know of a fix for this, so it might be a good idea to open a support ticket with Autodesk to make them aware of this.

[jR0sal3s]

thank you...for taking time..on this issue..

[jaroslav.petrovsky]

Hello jR0sal3s,

thank you for your report and feedback. I was also able to reproduce the problem, so I logged a defect under the number 105926. If you would like to check the status in future, please use this number.

[jR0sal3s]

we'd tried to patch a solution to this problem, for now, by changing the black part to other material that is similar to black and or lighter than black.  So it may be the parameter in the material itself that is causing it, or maybe a minute reflection from somewhere..so at least changing the material solve the problem..thanks all for your time.

jR

[mpatchus]

Check the black material and try adjusting the reflectivity 0%.

Whay you may be seeing is Inventor attempting to show a reflection on the surface.