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 Screen for Smooth SkinTones

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JhunRuby



Number of posts : 9
Age : 43
Location : Mandaluyong
Member since : 2009-09-08

PostSubject: Screen for Smooth SkinTones   Fri Nov 06, 2009 6:18 pm

What recommended screen type to smoothen skintones. We are currently using Hybrid Screen (XM screen) , smooth elliptical, 20-micron, 2540 dpi & 250 lpi but find that skin (result) prints grainy.

Any recommendations from the expert?

Neutral
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Alex Dulay



Number of posts : 108
Location : Manila
Member since : 2008-12-30

PostSubject: Re: Screen for Smooth SkinTones   Fri Nov 06, 2009 8:09 pm

Quote :
What recommended screen type to smoothen skintones. We are currently using Hybrid Screen (XM screen) , smooth elliptical, 20-micron, 2540 dpi & 250 lpi but find that skin (result) prints grainy.

You need a high quality source file. GIGO (garbage in, garbage out). (i'm no expert).
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Sandman

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Location : Middle East
Member since : 2007-11-21

PostSubject: Re: Screen for Smooth SkinTones   Fri Nov 06, 2009 11:35 pm

Expert kuno...hehehe.

Hi JhunRuby. I don't have a single answer for that since we can only suspect. Mukhang ok naman ang screening mo. Pero you have graininess sa skintones. However, if I encounter a similar situation I will be doing the ff:

CHECKING
1. check if graininess is evident on specific images, or on the entire sheet.
2. double check my plates if it's the correct one for this screen set

TESTING
a. transform the images from GCR to UCR-based seps. This will lessen the black on the skintones (presstech's advice)
b. change the dots from elliptical to round. This will shift the bumps on the midtones (skintone areas) toward the shadow area.
c. use a dotgain curve on the RIP that matches the ICC profile of the images
d. pray hard that it will work Very Happy

My humble thoughts lang po.

Larry
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Alex Dulay



Number of posts : 108
Location : Manila
Member since : 2008-12-30

PostSubject: Re: Screen for Smooth SkinTones   Sat Nov 07, 2009 4:08 am

Let me try to explain.

Hybrid/XM screening significantly affects highlights and shadow areas. If you will look at 1% tone, you will notice random/dispersed dots. At 99% you will see the same in reversed.

If you print in a very high LPI, hybrid/XM provides random dots that are still printable (in your case 20-micron) in the whole tonal value/range (gradient) and yet provide the benefits of smooth AM screening in the midtones. Thus every small detail in your original picture will be visible in the final print. (deleted my confusing statement here) Open your original photo, zoom in. You will see that your problem is from the source file.

Hybrid/XM is an excellent screening method. It requires a very good original photos and illustrations.


Last edited by Alex Dulay on Wed Nov 11, 2009 3:44 am; edited 1 time in total
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WORKFLOW

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Number of posts : 34
Location : Manila
Member since : 2009-10-21

PostSubject: Re: Screen for Smooth SkinTones   Sat Nov 07, 2009 9:30 am

JhunRuby wrote:
What recommended screen type to smoothen skintones. We are currently using Hybrid Screen (XM screen) , smooth elliptical, 20-micron, 2540 dpi & 250 lpi but find that skin (result) prints grainy.

Any recommendations from the expert?

Neutral

Hi JhunRuby,

For XM to be effective, you must determine your minimum highlight dot. To do this, you must print a testform with step wedge and determine at what highlight halftone dot area you start to "miss the dots". After you do this, you have to "calculate" (I have spreadsheet form to do this) your minimum highlight dot and set it in your RIP (if your workflow allows you to control your minimum dot). You can also do the same to your shadow areas (e.g. what area you start to clog).
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WORKFLOW

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Number of posts : 34
Location : Manila
Member since : 2009-10-21

PostSubject: Re: Screen for Smooth SkinTones   Sat Nov 07, 2009 9:57 am

@JhunRuby

In your case, say you start to lose the dots on the 8% halftone area;



Your minimum dot size should be set to 32.4 microns.
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Guest
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PostSubject: Re: Screen for Smooth SkinTones   Sat Nov 07, 2009 12:34 pm

Hi Jhunruby,

I would suggest that you investigate more on this issue. This can be a press or prepress problem. With your setting you should be printing ok. Tanong ko lang po are you printing linear plates or not?
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JhunRuby



Number of posts : 9
Age : 43
Location : Mandaluyong
Member since : 2009-09-08

PostSubject: Re: Screen for Smooth SkinTones   Sat Nov 07, 2009 4:50 pm

Shutter wrote:
Hi Jhunruby,

I would suggest that you investigate more on this issue. This can be a press or prepress problem. With your setting you should be printing ok. Tanong ko lang po are you printing linear plates or not?

curved na po ang plate! anyway, Thanks sa lahat ng response!

medyo malakas lang pala ang anti-set off powder kaya kapag backside printing
na ay lumalabas na ang grainy looks.

Smile
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Alex Dulay



Number of posts : 108
Location : Manila
Member since : 2008-12-30

PostSubject: Re: Screen for Smooth SkinTones   Sun Nov 08, 2009 3:59 pm

Quote :
For XM to be effective, you must determine your minimum highlight dot. To do this, you must print a testform with step wedge and determine at what highlight halftone dot area you start to "miss the dots". After you do this, you have to "calculate" (I have spreadsheet form to do this) your minimum highlight dot and set it in your RIP (if your workflow allows you to control your minimum dot). You can also do the same to your shadow areas (e.g. what area you start to clog).

Isn't it the purpose of XM screening is to reclaim the missing dots in highlights (1%-3%) and shadows (97%-99%)?
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