RE: Fix for 687294 psdcmyk device does not writeresolution correctly to PSD files

Igor,

>I can't review your algorithm because I have no knowledge about the  PSD
>format.
>The syntax looks perfect.

If you are really interested, I can send you a copy of the specifications.
My copy of Photoshop includes a copy of the Photoshop SDK.  The SDK
includes the specifications.  If you have Photoshop then you probably
also have the specifications.


>Don't know where it's fine to assume that HWResolution is an integer.
>I would code
>
>    (int) (pdev->HWResolution[0] * 0x10000 + 0.5);

There is no assumption that HWResolution is an integer.  It is defined
as a 'float'.  The value is cast to an integer only after multiplying
by 0x10000.  The cast is needed because Photoshop uses a 'fixed' format
for storing resolution.  The 'fixed' format consists of a 16 bit integer
and a 16 bit fraction.  The addition of 0.5 for rounding is minor but I
have added it to the code.


Dan



-----Original Message-----
From: Igor V. Melichev [mailto:[email protected]]
Sent: Saturday, February 14, 2004 12:58 AM
To: [email protected]
Cc: [email protected]
Subject: Re: [gs-code-review] Fix for 687294 psdcmyk device does not
writeresolution correctly to PSD files


Dan,

I can't review your algorithm because I have no knowledge about the  PSD
format.
The syntax looks perfect.

Don't know where it's fine to assume that HWResolution is an integer.
I would code

    (int) (pdev->HWResolution[0] * 0x10000 + 0.5);


Igor.

----- Original Message -----
From: "Dan Coby" <[email protected]>
To: "Gs-Code-Review" <[email protected]>
Sent: Saturday, February 14, 2004 11:37 AM
Subject: [gs-code-review] Fix for 687294 psdcmyk device does not
writeresolution correctly to PSD files


>
> Fix for 687294 psdcmyk device does not write resolution correctly to PSD
> files.
> This change adds a 'ResolutionInfo structure' into the 'Image Resources'
> section of the output file.  This structure specifies the horizontal and
> vertical
> resolution of the image.  (Note:  Adobe's support of asymetric resolutions
> is
> poor.)
>
>
> DETAILS.
> Index: src/gdevpsd.c
> ===================================================================
> RCS file: /cvs/ghostscript/gs/src/gdevpsd.c,v
> retrieving revision 1.5
> diff -u -r1.5 gdevpsd.c
> --- src/gdevpsd.c       10 Jul 2003 22:32:04 -0000      1.5
> +++ src/gdevpsd.c       14 Feb 2004 08:31:26 -0000
> @@ -999,7 +999,8 @@
>         chan_names_len += (separation_name->size + 1);
>      }
>      psd_write_32(xc, 12 + (chan_names_len + (chan_names_len % 2))
> -                       + (12 + (14*xc->n_extra_channels)));
> +                       + (12 + (14*xc->n_extra_channels))
> +                       + 28);
>      psd_write(xc, (const byte *)"8BIM", 4);
>      psd_write_16(xc, 1006); /* 0x03EE */
>      psd_write_16(xc, 0); /* PString */
> @@ -1035,6 +1036,19 @@
>         psd_write_8(xc, 2); /* Don't know */
>         psd_write_8(xc, 0); /* Padding - Always Zero */
>      }
> +    /* Image resolution */
> +    psd_write(xc, (const byte *)"8BIM", 4);
> +    psd_write_16(xc, 1005); /* 0x03ED */
> +    psd_write_16(xc, 0); /* PString */
> +    psd_write_32(xc, 16); /* Length */
> +               /* Resolution is specified as a fixed 16.16 bits */
> +    psd_write_32(xc, (int) (pdev->HWResolution[0] * 0x10000));
> +    psd_write_16(xc, 1);       /* width:  1 --> resolution is pixels per
> inch */
> +    psd_write_16(xc, 1);       /* width:  1 --> resolution is pixels per
> inch */
> +    psd_write_32(xc, (int) (pdev->HWResolution[1] * 0x10000));
> +    psd_write_16(xc, 1);       /* height:  1 --> resolution is pixels per
> inch */
> +    psd_write_16(xc, 1);       /* height:  1 --> resolution is pixels per
> inch */
> +
>      /* Layer and Mask information */
>      psd_write_32(xc, 0);
>
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