CMYK to Grayscale

CMYK to Grayscale

Post by Carrick H. Patters » Sun, 07 Jan 1996 04:00:00




> What's a good way to convert CMYK images to grayscale?

> The way I do it now is I go to the "Mode" menu and just
> select "Grayscale".  The problem with this is that I
> lose alot of detail and the result is a very flat looking
> image.

   As far as I know that *IS* the way to do it. You often then have to
fool around with levels and/or brightness-contrast, because a color pic
naturally looks more contrasty than a BW. There is also a "desaturate"
command, but I don't really see why you would want to use it if you are
really converting to BW.
   Hope this helps.

--
Carrick H. Patterson
Ginnaven Patterson Associates (advertising)

 
 
 

CMYK to Grayscale

Post by Kip » Sun, 07 Jan 1996 04:00:00


Attn: all (Macintosh)Photoshop gurus-

What's a good way to convert CMYK images to grayscale?

The way I do it now is I go to the "Mode" menu and just
select "Grayscale".  The problem with this is that I
lose alot of detail and the result is a very flat looking
image.

Thanks to all who reply.

Kip

 
 
 

CMYK to Grayscale

Post by Matt Bu » Mon, 08 Jan 1996 04:00:00


Quote:>> What's a good way to convert CMYK images to grayscale?

>> The way I do it now is I go to the "Mode" menu and just
>> select "Grayscale".  The problem with this is that I
>> lose alot of detail and the result is a very flat looking
>> image.

>   As far as I know that *IS* the way to do it. You often then have to
>fool around with levels and/or brightness-contrast, because a color pic
>naturally looks more contrasty than a BW. There is also a "desaturate"
>command, but I don't really see why you would want to use it if you are
>really converting to BW.
>   Hope this helps.

You might try this, which I use when going RGB->Grayscale:

1. Convert your color image to LAB by selecting LAB in the Mode menu.
2. Turn off the A & B channels.  You will see just the L (luminance)
channel displayed.
3. Select Grayscale in the Mode menu.  
4. Photoshop will ask you if you want to discard the A & B channels.  Say OK.
5. You're result: a grayscale luminance-based image.

I'm not sure if this makes as much a difference (if any) with CMYK, but
with RGB it makes a huge difference, especially in midtones.  Try it,
you'll see!

-Matt

 
 
 

CMYK to Grayscale

Post by Larry McKa » Mon, 08 Jan 1996 04:00:00


  Can anyone give me more info on their experiences with the Encad
Novajet Pro and/or the HP 755 Large Format inkjet printers?
  What about RIP? Computer RAM needed? What media it can print on?

  Thanks.

Shannon-

 
 
 

CMYK to Grayscale

Post by Michael J Pere » Mon, 08 Jan 1996 04:00:00




> > What's a good way to convert CMYK images to grayscale?

> > The way I do it now is I go to the "Mode" menu and just
> > select "Grayscale".  The problem with this is that I
> > lose alot of detail and the result is a very flat looking
> > image.

What I usually do is look at each channel, and decide which channel  
has the most detail and which has the least. Usually the C has the
most detail and the Y has the least, so I  delete the Y channel and
convert the CMK channels to grayscale, which gives me much better
detail.
 
 
 

CMYK to Grayscale

Post by Administrateur*Q » Wed, 10 Jan 1996 04:00:00


What's a good way to convert CMYK images to grayscale?

The way I do it now is I go to the "Mode" menu and just
select "Grayscale".  The problem with this is that I
lose alot of detail and the result is a very flat looking
image.

- Convert you iamge to Lab Mode;
- Select Split channels;
- keep only the Lightness channel.

It is also a good trick to convert a color scanned image (RGB) to grayscale!

Hope this help.

Louis Dery, R&D
TeleGraphique LC BBS
http://web.upc.qc.ca/TGLC/tglc.html

 
 
 

CMYK to Grayscale

Post by Matt Bu » Thu, 11 Jan 1996 04:00:00




>>> What's a good way to convert CMYK images to grayscale?

>>> The way I do it now is I go to the "Mode" menu and just
>>> select "Grayscale".  The problem with this is that I
>>> lose alot of detail and the result is a very flat looking
>>> image.

>>   As far as I know that *IS* the way to do it. You often then have to
>>fool around with levels and/or brightness-contrast, because a color pic
>>naturally looks more contrasty than a BW. There is also a "desaturate"
>>command, but I don't really see why you would want to use it if you are
>>really converting to BW.
>>   Hope this helps.

Just to follow up...

I compared mode changes CMYK->LAB->Grayscale with CMYK->Grayscale using
the Photoshop "fruit basket" photo.  Using LAB as an intermediate creates
much better midtones (using just the L channel of LAB when going to
Grayscale).  In the Photoshop manual, Adobe says that LAB *is* used as an
intermediate model for translations between models, but the results are
definitely better if you go through LAB manually.  Perhaps, LAB is not
used when going to grayscale, just between color models.

-Matt

 
 
 

CMYK to Grayscale

Post by Nidan J » Fri, 12 Jan 1996 04:00:00



> What's a good way to convert CMYK images to grayscale?

You can look in the channels if there is one that would do the job. If
not, than you can convert in CIE Lab, than take the ligthness channel. It
really depands on the image, but this should do the trick.

Nidan

 
 
 

1. CMYK to Grayscale


You can look in the channels if there is one that would do the job. If
not, than you can convert in CIE Lab, than take the ligthness channel. It
really depands on the image, but this should do the trick.

Nidan

Under the Mode menu, you will find CMYK and Grayscale. Simply select
Grayscale. PS converts CMYK files to Grayscale beautifully. No need to look
for that "right channel"

Iain

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