Ad
Ad
Ad
Pages: [1]   Bottom of Page
Print
Author Topic: Flatten Image Density Change  (Read 8777 times)
chriscor
Newbie
*
Offline Offline

Posts: 38


« on: April 21, 2006, 01:10:20 PM »
ReplyReply

I'm printing out BW images and prior to printing I'm flattening the images.  I just noticed that with some of the images when I flatten them there is a density change in the mid-tones.  The mid-tones lighten slightly when flattened.  Has anyone else experienced this?  What would cause this?  Several of the layers are in modes other than normal (ie  multiply, screen, luminosity ....).  Does flattening affect the layer modes?

Thanks

Chris
Logged
digitaldog
Sr. Member
****
Offline Offline

Posts: 8581



WWW
« Reply #1 on: April 21, 2006, 01:18:08 PM »
ReplyReply

IF you have layers with blending modes, this can most certainly happen.
Logged

Andrew Rodney
Author “Color Management for Photographers”
http://digitaldog.net/
marc.s
Jr. Member
**
Offline Offline

Posts: 91


« Reply #2 on: April 21, 2006, 01:28:25 PM »
ReplyReply

Quote
IF you have layers with blending modes, this can most certainly happen.
[a href=\"index.php?act=findpost&pid=63285\"][{POST_SNAPBACK}][/a]

Why? I don't recall ever having that problem and I always use tons of layers, including often with various blending modes.
Logged
digitaldog
Sr. Member
****
Offline Offline

Posts: 8581



WWW
« Reply #3 on: April 21, 2006, 01:53:47 PM »
ReplyReply

What version of Photoshop?

Does this appear visually at 100% view?
Logged

Andrew Rodney
Author “Color Management for Photographers”
http://digitaldog.net/
chriscor
Newbie
*
Offline Offline

Posts: 38


« Reply #4 on: April 21, 2006, 02:11:50 PM »
ReplyReply

Hi Andrew,

I'm using PhotoShop version 8.

I notice the change when viewing at 50% or lower.  Anything higher and there's no change.
I have two layers each with different opacity's set to multiply. The other layers are all normal.  The image is grayscale.  I'm checking on previous images I've flattened but haven't noticed the density change in other images.  Is there anyway to correct this?
Logged
med007
Full Member
***
Offline Offline

Posts: 110


WWW
« Reply #5 on: April 21, 2006, 02:21:24 PM »
ReplyReply

Quote
I'm printing out BW images and prior to printing I'm flattening the images.  I just noticed that with some of the images when I flatten them there is a density change in the mid-tones.  The mid-tones lighten slightly when flattened.  Has anyone else experienced this?  What would cause this?  Several of the layers are in modes other than normal (ie  multiply, screen, luminosity ....).  Does flattening affect the layer modes?

Thanks

Chris
[a href=\"index.php?act=findpost&pid=63283\"][{POST_SNAPBACK}][/a]

Chris,

I use a lot of layers with sometimes 40 or 50 layers and all blending modes. Mostly, when one does select all, copy merged and paste, the image is exactly as the component layers below. This occurs in 8 bit mode Adobe RGB. I can't remember whether or not it happens in 16 BIT mode.

It happens once in 30 times or so with complex multiple layers

So I add a second copy of the layer and then the color will be pretty well as expected and I again select all, copy merged and the new layer in a new document is normal 30% of the time.

Well what to do?

I add a curves layer and then go to multiply as the blend mode in a new document.

Here we have two ways of bringing back the tonality AND saturation to what you expect. One can change the slope of the mid tones with the introduction of a slight S curve and then reduce the percent of the layer to say 1-3% or so.

This can of course be done in two separate layers.

What is so fristrating is that sometimes everything is so perfect in a blend and one can't harvest the result even by all the tricks I know.

So I try to rebuild the image another way and use the un-harvestable layer stack as my target.

I imagine this is due to rounding off of numbers. Perhaps a different color space would be what we should be using, but then PS may not allow the layers we want?

I would love to know what we are doing wrong. It is certainly a problem.

I'm trying to remember whether or not it occurs in 16 bit images?

What bit level are you working in?

Asher
« Last Edit: April 21, 2006, 02:22:26 PM by med007 » Logged

[span style='color:blue']Journeys to the Masterpiece[/span]
digitaldog
Sr. Member
****
Offline Offline

Posts: 8581



WWW
« Reply #6 on: April 21, 2006, 02:41:18 PM »
ReplyReply

Quote
Hi Andrew,

I'm using PhotoShop version 8.

I notice the change when viewing at 50% or lower.  Anything higher and there's no change.
I have two layers each with different opacity's set to multiply. The other layers are all normal.  The image is grayscale.  I'm checking on previous images I've flattened but haven't noticed the density change in other images.  Is there anyway to correct this?
[a href=\"index.php?act=findpost&pid=63295\"][{POST_SNAPBACK}][/a]


OK, you should be OK on CS2; this is a visual issue with zoom ratio's. View at 100% (that's what you'll get). Older versions did have some issues depending on the blend modes and if you converted to other color spaces.
Logged

Andrew Rodney
Author “Color Management for Photographers”
http://digitaldog.net/
chriscor
Newbie
*
Offline Offline

Posts: 38


« Reply #7 on: April 21, 2006, 02:50:36 PM »
ReplyReply

Quote
What bit level are you working in?

Asher
[a href=\"index.php?act=findpost&pid=63299\"][{POST_SNAPBACK}][/a]


I'm in 8bit when I flatten
Logged
med007
Full Member
***
Offline Offline

Posts: 110


WWW
« Reply #8 on: April 21, 2006, 03:45:58 PM »
ReplyReply

Quote
I'm in 8bit when I flatten
[a href=\"index.php?act=findpost&pid=63304\"][{POST_SNAPBACK}][/a]
Chris,
Could you try to flatten it 16 BIT and see what happens?

Asher
Logged

[span style='color:blue']Journeys to the Masterpiece[/span]
marc.s
Jr. Member
**
Offline Offline

Posts: 91


« Reply #9 on: April 21, 2006, 05:26:04 PM »
ReplyReply

Quote
What version of Photoshop?

Does this appear visually at 100% view?
[a href=\"index.php?act=findpost&pid=63290\"][{POST_SNAPBACK}][/a]

Not sure if this was for me since I said I never noted this problem even though I'm big on layers (although not as many as 30-40). Anyway, I use a 'fit window to screen' view so I see the entire image when I flatten, and I've been using photoshop from 5.5 to CS2..
Logged
med007
Full Member
***
Offline Offline

Posts: 110


WWW
« Reply #10 on: April 21, 2006, 05:45:10 PM »
ReplyReply

Quote
Not sure if this was for me since I said I never noted this problem even though I'm big on layers (although not as many as 30-40). Anyway, I use a 'fit window to screen' view so I see the entire image when I flatten, and I've been using photoshop from 5.5 to CS2..
[a href=\"index.php?act=findpost&pid=63313\"][{POST_SNAPBACK}][/a]

Mark,

What blending modes do you use? It is possible that there are only certain combinations that do this. I use almost all the blending modes from PS 6 to CS2 and had this issue occur.

Asher
« Last Edit: April 21, 2006, 05:46:12 PM by med007 » Logged

[span style='color:blue']Journeys to the Masterpiece[/span]
Gabe
Full Member
***
Offline Offline

Posts: 146


« Reply #11 on: April 22, 2006, 02:16:00 PM »
ReplyReply

I have only ever seen this happen when viewing an image zoomed out; it's never happened at 100% view.

I'm thinking digitaldog is correct and that this is a result of PS rendering the file on the fly for whatever zoom level one has set..
Logged
marc.s
Jr. Member
**
Offline Offline

Posts: 91


« Reply #12 on: April 22, 2006, 04:10:04 PM »
ReplyReply

Quote
Mark,

What blending modes do you use? It is possible that there are only certain combinations that do this. I use almost all the blending modes from PS 6 to CS2 and had this issue occur.

Asher
[a href=\"index.php?act=findpost&pid=63318\"][{POST_SNAPBACK}][/a]

I typically use softlight, overlay and screen as well as color for hue layers.. sometimes I'll use any kind of wicked combination though.

I'm not sure about the 16 bit mode, because although I use that now I didn't with previous versions.. no idea what's going on, but it doesn't make sense for me that there should be a change when flattening the layers.

Perhaps you should try contacting photoshop support?
Logged
TimothyFarrar
Newbie
*
Offline Offline

Posts: 49


« Reply #13 on: April 22, 2006, 09:15:46 PM »
ReplyReply

Chris,

I know a way to fix this problem in CS and CS2, which might also work in previous versions.

In Photoshop, open up the Preferences dialog box. Then in the "Memory & Image Cache" section set "Cache Levels" to 1. Then restart Photoshop.

The problem with the image cache is that it works with smaller 8-bit source layers (even when editing a 16bit source image) when the view is zoomed out past 100%. This is done to speed up rendering to the screen, with a trade off in image quality (what you see might not be correct). This can be a serious problem with 16bit images and images that have some dithering.

Setting "Cache Levels" to 1, turns off the image cache and forces Photoshop to always render the screen using the full size 16-bit source images. So when you view at 50% or 25% you see exactly what you should see.

There are some disadvantages to turning cache levels off: Auto Levels will no longer work and some things run slower such as interactive adjustments in a Levels dialog.

Also note if Cache Levels is set to 1, the Histogram Pallet must not be open while processing because Photoshop will try to update the histogram after every small adjustment, such as moving a slider in a Levels dialog. This can slow Adobe Photoshop down to a crawl when editing large images.

Hope that helps,

- Timothy Farrar : farrarfocus.com
Logged

Timothy Farrar
Farrar Focus Digital Darkroom
www.farrarfocus.com/ffdd
opgr
Sr. Member
****
Offline Offline

Posts: 1125


WWW
« Reply #14 on: April 23, 2006, 03:50:45 AM »
ReplyReply

There is certainly something fishy in the cache images. I always see the following preview when displaying the Bill Atkinson Lab 33 image. If I switch on gamut warning there will appear single pixel lines which seem to be image data with a backward offset. This is with normal cache levels (4). With cache levels at 1 (or at 100% view) it is gone.

If there is some kind of misregistration in layers during the preview because of the zoom error, then it could certainly account for differences. I suppose though that misregistration will only happen if layers are of different sizes.

Logged

Regards,
Oscar Rysdyk
theimagingfactory
mobsterman
Newbie
*
Offline Offline

Posts: 8


« Reply #15 on: September 15, 2006, 12:03:59 AM »
ReplyReply

Hi all, I'm new here and I'm from a malaysian forum - photomalaysia.com.

I stumbled on a similar problem while flattening my layers - instead of relying on my eyes to see if there's a difference before and after flattening, I looked at the histograms. And indeed they were different.

I've posted some samples screenshots for all to examine and comment upon in this thread: What happens when you flatten your layers?:

if that does not work here's the cut-n-paste string:
http://www.photomalaysia.com/forums/showthread.php?t=16222

Really appreciate if anyone can explain / comment on this phenom.

Thanks
Logged
TimothyFarrar
Newbie
*
Offline Offline

Posts: 49


« Reply #16 on: September 15, 2006, 08:17:37 PM »
ReplyReply

I think, the histograms when Cache Levels are > 1 are generated from the image cache so after flattening, then you should see a difference.
Logged

Timothy Farrar
Farrar Focus Digital Darkroom
www.farrarfocus.com/ffdd
mobsterman
Newbie
*
Offline Offline

Posts: 8


« Reply #17 on: September 15, 2006, 11:18:40 PM »
ReplyReply

Quote
I think, the histograms when Cache Levels are > 1 are generated from the image cache so after flattening, then you should see a difference.
[a href=\"index.php?act=findpost&pid=76527\"][{POST_SNAPBACK}][/a]
Timothy, thanks for having a look. I'll try it with cache=0. Cheers.

Anyone else? Strange phenomenon!
Logged
mobsterman
Newbie
*
Offline Offline

Posts: 8


« Reply #18 on: September 16, 2006, 12:17:42 AM »
ReplyReply

Oops, actually cache=1 is the minimum. My mistake. Works fine now! Timothy, thanks again, you're a genius!
« Last Edit: September 16, 2006, 12:18:38 AM by mobsterman » Logged
to-mas
Newbie
*
Offline Offline

Posts: 41


« Reply #19 on: September 25, 2006, 02:08:45 PM »
ReplyReply

cool
I had this problem for so long and never found a solution.

thanks
Logged
Pages: [1]   Top of Page
Print
Jump to:  

Ad
Ad
Ad