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Reduced colors when saving as TIF in Paintshop Pro

I'm using Paintshop Pro 7.04.  I've got some large (8x10 inch, 300 dpi) black-and-white images that I am trying to save as TIF files.  After all my fine, anal work getting the tonality of the images just right, I save them to TIF and they appear darker and a bit blotchy -- rather like the contrast has been turned up a bit on them, and like their resolution is lower (it's not).  Also, they lose some of their shades of gray: one dropped from 1571 in PSP to only 1500 in the TIF.  Another went from 256 to 200.  A third went from 256 to 221.

I thought TIF was a "lossless" compression, but I've lost colors as well as quality.  What gives?  They were saved with LZW compression, CMYK color channels.

--Galisteo8
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Galisteo8
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Galisteo8
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3 Solutions
 
Mark_FreeSoftwareCommented:
>>They were saved with LZW compression
try it without that

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lherrouCommented:
Galisteo8,

Hmmm. TIF _is_ a "lossless" file format. Whne you are saving, are you making sure that the CYMK box is checked, or are are they being converted to the RGB color space? This seems like the most likely issue, and WILL effect the color spectrum in the images. The LZW compression shouldn't make a difference, but, as Mark_FreeSoftware says, it's worth a shot changing the checkbox to "Uncompressed". Last, but not least, do you have layers in your TIF? The TIF file format can support layers, but I've noticed that PSP doesn't handle them very well, so they may be being reordered or dropped when you re-open the file.

Cheers,
LHerrou
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Galisteo8Author Commented:
LZW was checked by default, so I left it.
CMYK was checked when I saved.

1) The PSP file(s) do have layers.  I guess I could try merging the layers and then saving...

2) Is it possible I created the images in RGB and the problem occurs when "converting" them to CMYK?  I don't know what the default color-type is for PSP...

3) How can I check a file to see what color-type it's using: RGB or CMYK?
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Mark_FreeSoftwareCommented:

>>2) Is it possible I created the images in RGB and the problem occurs when "converting" them to CMYK?  I don't know what the default color-type is for PSP..
yes this is possible

RGB is the exact opposite of CMYK

RGB is used for displaying on a screen, CMYK is used for printing



make sure you have the latest patch, since i saw a patch for version 10 that corrected problems with TIFF files

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lherrouCommented:
>>2) Is it possible I created the images in RGB and the problem occurs when "converting" them to CMYK?  I don't know
>>what the default color-type is for PSP...

The default for PSP is RGB, so that's likely to be the problem. The following tidbit below is from my PSP 8.x version's Help file:
"Although you cannot create or edit an image using the CMYK model, you can still split the image to four channels: cyan, magenta, yellow, and black."

So if you are saving as CMYK, you are forcing PSP to convert the image at the end of your taskwork, with no control over the results.
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Galisteo8Author Commented:
>RGB is used for displaying on a screen, CMYK is used for printing

So... How then does one look at a CMYK image on a screen?
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Mark_FreeSoftwareCommented:

>>So... How then does one look at a CMYK image on a screen?
it is converted by programs lik photoshop, or psp

it can be viewed, but the color information can differ slightly
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lherrouCommented:
The following may be useful for better understanding: http://en.wikipedia.org/wiki/Cmyk

If you are working in grayscale, keep your tifs in RGB. If they are intended for print, talk with your printer about your workflow before attempting any largescale print jobs - PSP is less than ideal for most print work, it is primarily for editing photos for electronic presentation (works fine if you're making 4 X 6s at your local photoshop, etc, though).
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Jose ParrotGraphics ExpertCommented:
Hi,

Compression on TIFF is determined by PackBits, which is often ineffective on continuous tone images, including many grayscale images. In such cases, it is better to leave the image uncompressed. In the other hand, LZW compression is a heuristic one, no loss.

Conversions from RGB to CMYK can cause problems due a factor called Luma related to each R, G and B colors. As this setting isn't available in PSP, it is supposed to be optimal.

PSP works TIFF with a pallette or not, for both color and gray.
For paletted gray scales there are from 1 to 8 bits/pixel, that is 2 to 256 shadows of gray, selected from a color map of 64K colors. So it can be frustrating to watch a 64K colors per pixel image in the screen to lost that color resolution to only 256.

There are the following TIF file options:
TIFF-No Compression - Bits-per-pixel: 1, 4,8,24.
TIFF-Huffman - Bits-per-pixel: 1.
TIFF-Pack Bits - Bits-per-pixel: 1, 4,8,24.
TIFF-LZW - Bits-per-pixel: 1, 4,8,24.
TIFF-Fax Group 3 - Bits-per-pixel: 1.
TIFF-Fax Group 4 - Bits-per-pixel: 1.

So, try to chose the 24 bits per pixel color resolution, turn the image to grayscale (and retouching it as you use to) and save it as a full color 24 bits per pixel. About compression, if pack or LZW is for 24 bits too, there is no loss.

Regards,

Jose
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lherrouCommented:
>> Compression on TIFF is determined by PackBits, which is often ineffective on continuous tone images, including many
>> grayscale images. In such cases, it is better to leave the image uncompressed. In the other hand, LZW compression is a
>> heuristic one, no loss.

This is a bit unclear. To clarify, PackBits is one of several methods of compressing TIF images. It is commonly used for scanned documents, and is a lossless compression method which is highly effective for bi-tonal (black and white) images, although it can be used on images with greater bits-per-pixel. LZW is another lossless compression method, and is highly effective for greyscale and color images where the color exists in large blocks - this compression works in large part by recognizing repeated identical strings in the data, and replacing the many instances with a single instance and a repeat factor. For example, it is shorter to say "red*23" than it would be to say "red" twenty-three times.
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Galisteo8Author Commented:
>>So, try to chose the 24 bits per pixel color resolution, turn the image to grayscale (and retouching it as you use to) and save it as a full color 24 bits per pixel. About compression, if pack or LZW is for 24 bits too, there is no loss.

So, before saving to TIFF I need to configure my black-and-white (grayscale) image as "full color"?

Also, I am wondering... Why would a publisher need CMYK if the image is black-and-white?
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lherrouCommented:
Try just unchecking the CMYK box before you save. You shouldn't have to do anything else. If you are sending this to a printer or publisher, you should probably upgrade to Photoshop, but as I said, don't do anything before talking to the printer/publisher.
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Galisteo8Author Commented:
In addition to questions posted above moments ago...  Which of the following most resembles my likely problem:

1) With PSP, I am trying to save a file as a TIF file.
2) With PSP, I am trying to save a file in CMYK color space.
3) I am trying to convert an image from RGB color space into CMYK color space, regardless of the image editing software I am using.
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lherrouCommented:
#3 - you are converting a RBG file into a CMYK color space (which is producing the color changes you see)
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Galisteo8Author Commented:
>If you are sending this to a printer or publisher, you should probably upgrade to Photoshop

Does Photoshop simply handle the CMYK conversion better?  Since RGB --> CMYK is an issue, what difference will PS make?
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lherrouCommented:
First, Photoshop will allow you to work in a native CMYK color space, and see the results on screen as close to the desired colors as possible. You won't need to convert to CMYK after the fact. Also, you will get better handling of color profiles for your images. There are a lot of other capabilities of Photoshop that I won't go into here, but suffice it to say that it is the industry standard for a reason.
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Galisteo8Author Commented:
I do have some limited access to Photoshop.  So, are you telling me that if I go the Photoshop route I will have to start over with the original fresh-from-the-camera photos?
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lherrouCommented:
I find the algorithm in Photoshop for converting between CMYK and RGB to be pretty accurate. There's no direct match between these two color spaces (did you read the Wikipedia link?), so all software converts, but the conversion may be more or less accurate.

I don't know what your workflow has been - have you been saving your touched-up photos in PSPs native format, as well as in TIF? It may be that you will be fine just saving RGB TIFs, so you won't have the issues of loss of shades.
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Mark_FreeSoftwareCommented:
>>So, are you telling me that if I go the Photoshop route I will have to start over with the original fresh-from-the-camera photos?

no, you can import psp files
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Jose ParrotGraphics ExpertCommented:
Hi,

Packed isn't the best option for grayscale images. Better to use the LZW.
But compression it is not the source of the problem.
BTW, conversion RGB <--> CMYK isn't the problem also.

Just to remember, there are the following TIF file options, important in our case:
TIFF-No Compression - Bits-per-pixel: 1, 4,8,24.
TIFF-Pack Bits - Bits-per-pixel: 1, 4,8,24.
TIFF-LZW - Bits-per-pixel: 1, 4,8,24.

What PSP does in the screen is to show 24 bits per pixel images. That's why you watch "infinite" intermediate shadows. If the TIF file is saved in 8 bits per pixel will have up 256 shadows in the grayscale, so a lot of them will be eliminated, after reduced to a 256 color palette.

Unfortunately I don't know the internals of PSP to guarantee how to record an image with 24 bits per pixel of gray tones. That's why I suggested to TRY save the image in full 24 bits per pixel color, to use all the same 24 bits per pixel used in the screen. I agree, sounds strange... but it is a trying to understand if the problem is related to BIT PER PIXEL relationship. May be, or not...

An interesting checking is to observe the palette, in verifying how much (and what) colors are there. My guess is in this direction: the palette. Take a look at "Count image colors", "Image Information", the Manual Color Correction tool (how are the curves linearities?), Histogram Adjust (mainly the Output max and the Middletone adjust), and finally the HUE controls.

Regards to all,

Jose
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Galisteo8Author Commented:
I'm reading the Wikipedia article now (thanks for the URL).  But I still wonder... What is served by converting a black-and-white image to CMYK???
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lherrouCommented:
The printer's process is a CMYK process, so the image must be in that format when they print. You can do the conversion yourself, or they can do it... I prefer to do any conversion where I can see the output and results (and tweak if necessary).
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Galisteo8Author Commented:
The bits-per-pixel stuff may have been the important part.

Saving the PSP file as a jpg, I opened it on a computer with Photoshop.  There I ensured that it was 300 dpi, 8x10 as needed... but also set it to be at least 16-bit (I may have upped it to 24- or 32-bit -- I'm not at that computer right now) as well as switching the Mode to CMYK. and THEN saved it as a TIFF with LZW compression.  It appears to be, on-screen, as good as the original image.  10x bigger, but looks just as good.  :)

Perhaps on my PSP at home it was (likely) RGB, but may also have been only 8-bits.  I'll have to check on that.

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