What Happens to "White" Areas in a Line Drawing?

MM
Posted By
Marie_Maier
Oct 18, 2008
Views
412
Replies
9
Status
Closed
Various filters in PS 7 allowed several good line drawings of a building needed for a brochure. However, these images are supposed to be "transparent" so a colored paper shows underneath.

I assumed the printer would photograph the drawing to make a black plate and the white spaces in between wouldn’t show. Oh, oh–what if I’m wrong? If I am, what does the printer or me have to do to get rid of all those white spaces?

Hope there are some printers here who can explain this?

Thanks very much!………………..mm
Related Tags
area draw happen line white

MacBook Pro 16” Mockups 🔥

– in 4 materials (clay versions included)

– 12 scenes

– 48 MacBook Pro 16″ mockups

– 6000 x 4500 px

M
Mylenium
Oct 18, 2008
In print there is no such thing as transparency. You only have ink areas and the substrate. On a basic level your considerations are right, but it still comes down to providing the info in the correct format. Therefore your file must be in greyscale mode, duotone or CMYK, taking care to create a clean black channel and leaving the other channels empty….

Mylenium
MM
Marie_Maier
Oct 18, 2008
OK Mylenium,Thanks for the reply. I got some of this. Yes, the drawings are in CMYK, they are on a transparent background, and are in greyscale.

How do I make sure the other channels are empty? I just checked one of the drawings for Channels, and only gray was shown. Did I do something right?
MM
Marie_Maier
Oct 18, 2008
OK Mylenium,Thanks for the reply. I got some of this. Yes, the drawings are in CMYK, they are on a transparent background, and are in greyscale.

How do I make sure the other channels are empty? I just checked one of the drawings for Channels, and only gray was shown. Did I do something right?
MM
Marie_Maier
Oct 18, 2008
Next question: What if you DO want the white spaces to print, what do I do and what does the printer have to do differently?

As a test, I took one of the images and placed in on a new RGB backbground. I put a red fill under it. HECK! there was white in that same image! Isn’t it supposed to be just black?

I’m confused…………..m
M
Mylenium
Oct 19, 2008
You can clear out other channels by simply using adjustment tools to set the black and white points while only one channel is being displayed. If it’s perfectly white, it will be empty. This should allow you to get rid of the minute residues of Cyan and Magenta that conversions from RGB or some paint operations may have introduced.

You can invert channels in PS easily and for the actual physical print you’d do just that or the printer simply flips a switch to invert the data during the plate setting process. Simulating colored prints on your home printer would of course require the document to have proper transparencies. You can easily create them by using Select –> Load Selection and then referring to the Black channel in your document, then removing/ masking the areas not needed.

Mylenium
MM
Marie_Maier
Oct 19, 2008
So sorry Mylenium, I don’t understand this. I opened one of the images, only the gray channel shows and then opened adjustments>curves, and tried levels too, but I don’t see how to remove the white.

Should I have started with the colored photo first before it was changed to grayscale? Even with the colored photo and channels open, I don’t see how to modify the channels. Sorry to be so dense…this whole thing of changing a photo to a line drawing is new to me….thanks for your patience……….mm
M
Mylenium
Oct 19, 2008
If your images are in greyscale mode, than you don’t need to do anything more for printing. The densities may not be right, but a printer could use them right away to generate a printing plate. The above steps only apply to composite images in CMYK mode.

Mylenium
MM
Marie_Maier
Oct 19, 2008
Thank you, thank you, thank you and I hope the printer has the same understanding.

I can’t visualize how the printer gets rid of all the subtleties of white spaces and the larger ones too, to obtain only the black and gray areas so those former white spots are now non-existant and are transparent. Beats me!

If you can explain how this magic occurs, I’d love to pass it on to my cohort who is wondering the same thing.She sees the white image spaces as I do………….m
J
Jim
Oct 19, 2008
wrote in message
Thank you, thank you, thank you and I hope the printer has the same understanding.

I can’t visualize how the printer gets rid of all the subtleties of white spaces and the larger ones too, to obtain only the black and gray areas so those former white spots are now non-existant and are transparent. Beats me!

If you can explain how this magic occurs, I’d love to pass it on to my cohort who is wondering the same thing.She sees the white image spaces as I do………….m
No, the printer driver has no "understanding". And, the printer only does what the printer driver tells it to.
"White" areas in a printed output are those in which no ink of any color are present. What the other posters instructions do is eliminate extraneous colors which can happen during the conversion from RGB output to CMYK output. You do realize don’t you, that printer drivers expect RGB images? And, you do realize that white in the RGB space is R=G=B=255? Furthermore, you should understand that converting from R=G=B=255 to C=M=Y=K=0% is necessary but sometimes impossible to achieve whithout further changes to the RGB image.
Jim

How to Master Sharpening in Photoshop

Give your photos a professional finish with sharpening in Photoshop. Learn to enhance details, create contrast, and prepare your images for print, web, and social media.

Related Discussion Topics

Nice and short text about related topics in discussion sections