Film-Tech Forum ARCHIVE: Upscaling on an ICMP/Alchemy

This is topic Upscaling on an ICMP/Alchemy in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Carsten Kurz (Member # 5396) on 08-23-2017, 05:15 PM:

Not going into the pros and cons of excessive cropping or scaling - I want to show a DCP with a 2.55 aspect ratio in a 2k scope container on a screen with approx 2.12 ar, but filling the full screen. Usually that involves croping the sides of the 2.55 image down to approx 2.12 and then using the lens zoom to fill the screen.

Now, doing that, I notice that the 2.55 image only uses 804 vertical pixels. Cropping the sides, I end up with an image of around 1704 by 804 pixels, wasting imager estate and thus light both above/below as well as right and left (pillar AND letterboxing). Now, I thought I should be able to enlarge/rescale the image from 1704 to 2048 horizontally, coming out around 966 pixels vertically. The Barco Alchemy offers me a combined resize/masking option in Communicator, but it seems I can only downscale, not upscale the image there. Any idea how this could be accomplished?

The task sounds rather weird for DCP content - but I would end up with the same problem if e.g. I wanted to show a 720p source through HDMI or DisplayPort full screen, no?

- Carten

Posted by Dave Macaulay (Member # 813) on 08-23-2017, 09:06 PM:

I believe you can connect with the TI ICP program and access its more comprehensive scaling controls? The ICMP contains pretty much a TI ICP.

Posted by Carsten Kurz (Member # 5396) on 08-24-2017, 04:24 AM:

I think the ICMP contains all the ICP functionality, but doesn't emulate an original TI ICP?

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 08-24-2017, 05:32 AM:

I don't think the Alchemy really would need to emulate an original TI ICP, since it's just their own stuff interfacing with it. Bypassing the original ICP is probably also the only way to support stuff like 4K@60FPS.

I'd be interested in a solution to up-scale content with the Alchemy though.

Posted by Tom Bert (Member # 5719) on 08-24-2017, 08:59 AM:

In Communicator SW, browse to “Configuration" --> "PCF”
Click “Active area” button.

In the “Active area” window fill in:
Width = 1704
Height = 804
X offset = 172
Y offset = 138

Posted by Carsten Kurz (Member # 5396) on 08-24-2017, 04:58 PM:

Thanks Tom, Ill try. I found a 'visually' working solution using the 'letterbox' function, but I can't control it numerically as in the PCF setup, so I am not sure wether the resulting AR is correct. But 'Ill try cropping with the active area function.

- Carsten

Posted by Carsten Kurz (Member # 5396) on 08-25-2017, 04:28 PM:

Hmm, I tried it - and it 'nearly' worked... Unfortunately, and this may qualify as a bug report, there are timed text subtitles in that DCP, and they get garbled whenever I reduce the active image area vertically. The image does what it should, but the subtitles suddenly turn up in the upper quarter of the image area, and look like static noise (in the original color of the subtitles).

So, currently, I am left with masking and losing quite some light. I am using the latest version of the ICMP and 6E software.

- Carsten

Posted by Tom Bert (Member # 5719) on 08-28-2017, 07:01 AM:

Does it count as a bug if we know that subtitle rendering would be messed up? :-P

Thanks for flagging: noted

Posted by Carsten Kurz (Member # 5396) on 08-28-2017, 07:41 AM:

Thanks Tom, I guess I did not get the idea of the 'letterbox' function in screen file configuration completely - it may appear that, if disabled, what it does in this case is, scale the vertical container dimensions to full imager height, and crop away the sides, maintaining square pixel AR? That way, I would basically end up with an 1.9AR image, but could still crop it further? Because, the subtitle issue does not come up then. It's just that I have less control about the specific part of the image/AR that I want to use.

I guess I need to make a few test sequences to get this sorted out.

- Carsten

Posted by Steve Guttag (Member # 268) on 08-28-2017, 10:24 AM:

Historically, (going back to the Mark VII machines, at least), the "Letterbox" checkbox, if ticked meant that the TI board will scale until the image hit the width of the imager and if unticked it would scale until the image hit the height of the imager (cropping the sides).

It used the input resolution as its guide to scaling the image.

Back in the day, I used to use the "letterbox" function by unticking it so that Standard Def signals with a 16x9 letterbox within them (16x9 image within a 4x3 raster) would be scaled in the projector to show as 16x9. This sort of situation is all but gone now as very few standard def sources are in use anymore that would have a letterboxed image inside. Most DVDs will have an anamorphic image that uses the full 4x3 raster to get as much resolution to the 16x9 final output.

Another key to using the projector's scaler is to understand the input dimensions are what tells the scaler how much to scale. As you go with smaller dimensions, the scaler applies more magnification to bring those dimensions to the limits of the imager. This was true of Barco's scalers too. I had a whole table to use for the ACS2048 (or ImagePro) to get most any SD source to scale right and maintain aspect ratio.

I have not used the Alchemy yet (but I have one in the dock now so that is going to change). I presume that Barco has continued the same logic as was used in their own products of the past as well as mimic what TI has done.