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Super blacks issue
Having a weird issue – import graphic (mostly black and white design filling most of the screen… Now when I scale the graphic or add Gaussian blur I get heaps of super black spikes on my external skopes. Rendered and still get the spikes. Not sure what’s going on or a way to fix this issue…? Worried about qc at the network.
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9 Replies
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Type of graphic file? bit depth? alpha channel? sequence settings?
…all the detail you can give would be helpful.
TimK,
Director, Consultant
Kolb Productions,Adobe Certified Instructor
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Hi Tim,
The file is a RGB 8 bit .psd. It’s basically a white box with black text and a black box with white
text and white logo in it 1280 x 820. Sequence is 1920x1080i 50i ProRes HQ as the render codec. The super blacks appear after render on internal waveform skopes and external waveform skopes via AJA Kona LHi SDI.Happens if I set sequence to ‘composite in linear colour’ or without as well. I’ve saved as .png from Ps and get the same issue. It’s fine without any filters – but when I add a gaussian blur to get rid of flicker I get the row of super black spikes down to about 0.25 on the Pr YC waveform once rendered.
Cheers,
Mike
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I’m on Windows, so I don’t typically work in QT or ProRes…
For sake of testing, what happens if you use a different sequence preset that doesn’t use ProRes as the preview codec?
In Photoshop, are the whites full 255 and black set to absolute zero?
TimK,
Director, Consultant
Kolb Productions,Adobe Certified Instructor
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Yes in Ps blacks are 0 and Whites are 255. I set sequence renderer to ‘I Frame only MPEG’ and get the same issue…
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Have you created 8 bit graphics in the past with black at 0 and white at 255 without any issues?
Typically I still stick with the old safety values of black at 16 and white at 235.
If white is set at 255, I assume it’s maxed out too?
I have no idea why you wouldn’t see the problem before rendering…I would have thought they’d be evident all the time.
TimK,
Director, Consultant
Kolb Productions,Adobe Certified Instructor
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Haven’t really noticed this issue in the past. I might test in FCP7 to see if the same thing happens…
The graphic was supplied to me – I bring the whites down to around 94% before exporting – blacks I keep at 0.
It seems to be where the black background meets the white text that is causing the problem when the
gaussian blur is applied. Can you replicate the issue at your end? i.e. In Ps make black background, make a row of small white text – export file – put in Pr sequence and add gaussian blur then render and look at the
YC Waveform… -
Well…if I make a PSD that has black at 16 and white at 235, I see the black level dip at the blurred edge (but the black level maps high on that document anyway)…if I use a 0-255 document, then I don’t see the issue, and it maps correctly on the scopes. The behavior seems consistent for both CS6 and CC on Windows…with or without rendering a preview.
TimK,
Director, Consultant
Kolb Productions,Adobe Certified Instructor
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Thanks for testing, Tim 🙂 Weirdness. I think I’ll export the .psd to .png (it has heaps of smart layer etc) and blur that before importing to Premiere Pro CC.
It could be a bug – hope Adobe read this and test at their end.
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Make the Ps document at the largest anticipated size with an alpha channel. It should then scale smoothly without artifacts when imported.
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