Vesku Posted November 30, 2014 Share Posted November 30, 2014 Can I have 4:4:4 1080P ETC if I use 4k and 2x digital zoom? It is then 100% sensor upscaled to 200%. With 4k I can then downsample to 4:4:4 fullhd. Quote Link to comment Share on other sites More sharing options...
SleepyWill Posted November 30, 2014 Share Posted November 30, 2014 In theory, you can use the GH4 to get 1080p 4:4:4 footage at 10bits. In practice however, having to work with 4k files and adding a really frustrating and time consuming step into your workflow renders this relevant to very few people, currently. http://www.eoshd.com/2014/02/discovery-4k-8bit-420-panasonic-gh4-converts-1080p-10bit-444/ Quote Link to comment Share on other sites More sharing options...
Vesku Posted November 30, 2014 Author Share Posted November 30, 2014 I mean 8bit 4:4:4 ETC when downsampling from 8bit 4k 4:2:0. I must test if 4k 2x digital zoom is good upsampling. Quote Link to comment Share on other sites More sharing options...
SleepyWill Posted November 30, 2014 Share Posted November 30, 2014 I mean 8bit 4:4:4 ETC when downsampling from 8bit 4k 4:2:0. Really? You would choose to needlessly throw out colour data? I suppose if you don't have a 10bit monitor & graphics pipe, you really need to! I'm fairly sure you can do this, but is it worth it for 444?? Quote Link to comment Share on other sites More sharing options...
Guest Ebrahim Saadawi Posted December 1, 2014 Share Posted December 1, 2014 To get the highest quality image out of the GH4, is shooting 4K 4:2:2 10bit in the Atomos Shogun in ProRes HQ 10bit through the HDMI port. This the most pixel count and most colour information and least compression the camera has to offer. You take that ProRes 4K file and do what ever you want in 4K, but if you are going to crop/reframe remember to downscale the output to 1080p in the end render. Remember that crop modes are only relevant when the camera is not giving you every pixel (like a 4K GH4 does or 21mp stills on a DSLR for example), when the camera downsamples/lineskips internally to a smaller pixel count than the area it's deriving the image from, then it's useful to use a smaller different part of the sensor in the center to get a crop effect without downsampling, but when it's already using the entire sensor and giving you the full resolution, there is no point, you take it and crop in post, that's why DSLRs don't have a crop mode for photography, because there is no point in cutting the edges in-camera if you can do the same in post more percisely. If your output is 1080p you can do some very heavy cropping in post in the GH4 4K files, all the way to a s16 size sensor and still have around 2K of resolution. Quote Link to comment Share on other sites More sharing options...
jax_rox Posted December 1, 2014 Share Posted December 1, 2014 If your output is 1080p you can do some very heavy cropping in post in the GH4 4K files, all the way to a s16 size sensor and still have around 2K of resolution.Let's not confuse things here. You can crop right in on 4k files - 4k is 4x the size of 2k, you can actually crop into a quarter of the frame if you wanted to. That, however, does brings up issues like lens resolving power and all the rest of it.It's not really equivalent to a S16 sensor, however - let's not confuse post cropping with sensor sizes. Quote Link to comment Share on other sites More sharing options...
Vesku Posted December 1, 2014 Author Share Posted December 1, 2014 Is there anybody who understands my idea. It is to get high magnification video with i.e. 100-300mm lens and 444 fullhd. Better than normal ETC. Better than cropped 4k. Internally. Quote Link to comment Share on other sites More sharing options...
Guest Ebrahim Saadawi Posted December 1, 2014 Share Posted December 1, 2014 Let's not confuse things here. You can crop right in on 4k files - 4k is 4x the size of 2k, you can actually crop into a quarter of the frame if you wanted to. That, however, does brings up issues like lens resolving power and all the rest of it. It's not really equivalent to a S16 sensor, however - let's not confuse post cropping with sensor sizes. It is equivalent to changing to a smaller sensor size. To OP: I explained the highest quality way to get a crop out of the GH4 above. Anything else would lose quality. And no the GH4 does not record or output a 4:4:4 signal, maximum is 4:2:2. Some people claim that if you have a 4K 4:2:0 video and downscale it to 1080p it becomes 4:4:4 1080p. But anyhow the highest quality crop mode you can get from the GH4 is recording 4K 4:2:2 10bit externally and cropping in post to the desired image. Quote Link to comment Share on other sites More sharing options...
Guest 560a4aedcb80685284629074497fdc75 Posted December 1, 2014 Share Posted December 1, 2014 Tests have shown that etc in 1080 mode is superior to cropping the 4k image in post. I'll link a video when I'm home later. Quote Link to comment Share on other sites More sharing options...
SleepyWill Posted December 1, 2014 Share Posted December 1, 2014 Is there anybody who understands my idea. It is to get high magnification video with i.e. 100-300mm lens and 444 fullhd. Better than normal ETC. Better than cropped 4k. Internally. The act of converting 4k output to 444 will reduce it to 1080p. If you perform a digital zoom, you will have to bring the resolution even lower. It will be the exact same quality as if you digitally zoomed 1080p footage anyway, except it will be 444, which you won't notice. And trust me, the added work in using an external recorder is a drop in the ocean compared to the hell you will put yourself through by adding all these processes in post! Quote Link to comment Share on other sites More sharing options...
Nikkor Posted December 1, 2014 Share Posted December 1, 2014 If I cut a dollar note intro two, I got two dollars. Is there anybody who understands my idea? Quote Link to comment Share on other sites More sharing options...
Vesku Posted December 1, 2014 Author Share Posted December 1, 2014 I tested a little 4k+2x digital zoom vs fullhd+ETC. Both read 100% sensor pixels but 4k 2x seems to be sharper. So if I want the best magnification 4k is better than ETC. I dont know if it does 2x digital zoom before or after 4:2:0 color sampling. Seems that the colors are not improving very much compared to 100% ETC. The sensor is noisy and a bit blurred anyway at 100%. Sample frames: http://***URL removed***/forums/post/54842900 Quote Link to comment Share on other sites More sharing options...
SleepyWill Posted December 1, 2014 Share Posted December 1, 2014 I tested a little 4k+2x digital zoom vs fullhd+ETC. Both read 100% sensor pixels but 4k 2x seems to be sharper. So if I want the best magnification 4k is better than ETC. Sample frames: http://***URL removed***/forums/post/54842900 It would be a lot more conclusive if the two pics were lit better and framed identically Quote Link to comment Share on other sites More sharing options...
Vesku Posted December 1, 2014 Author Share Posted December 1, 2014 It was a quick test in bad light. Iso was 200 and there is lots of sharpening and added color. I tried to figure if color res is better. I must test more in good light. Still seems that 4k 2x is the way to go if a high magnification is the goal. But no 60P then. Quote Link to comment Share on other sites More sharing options...
kerplunk Posted December 2, 2014 Share Posted December 2, 2014 If I understand things right, when comparing 4K to ETC you're looking at noise being averaged among 4 pixels versus 1:1 using ETC. So it makes sense that 4K appears to have less noise - even at 2x. Quote Link to comment Share on other sites More sharing options...
Guest Ebrahim Saadawi Posted December 2, 2014 Share Posted December 2, 2014 You have a sensor that contains 4096x2160 pixels (it's a bit bigger for stills but lets simplify). When you set the camera to ETC, the sensor uses the centre 1920x1080 pixels, throwing put all the remaining ones. Using a smaller sensor on the same lens gives that magnification effect, plus deeper depth of field. In 4K mode, the camera recods the entire pixels, which gives you the centre 1080p pixels plus the remainin ones outside. This way you can throw them away later and use only the center portion again by cropping. Now in terms of colours, the GH4 records internally in 4:2:0 8bit in bith the 1080p etc and 4K. It outputs a 4:2:2 10bit signal also in 4K. So your best chance to get highest quality colour is to shoot in 4K 4:2:2 10bit and crop in post. This will give you a 1080p 10bit 4:2:2 ETC image. Also if the GH4 can ouput 4:2:2 10bit 1080p in ETC mode, you can use that, bypassing the post-cropping step. Using the 4K mode though will give you more freedom in cropping choice. If you want to do it internally the best way is shooting 4K and cropping. From my tests there is no advantage in using the ETC mode unless you're not planning to do any post work. The internal 4K 4:2:0 8bit is a magnificant image by the way and you don't really need much more than that for anything. But since you're asking for 4:4:4 then the 10bit 4:2:2 4K shogun suggesstion had to be pointed out. It's 2 thousand dollars. Quote Link to comment Share on other sites More sharing options...
jase Posted December 2, 2014 Share Posted December 2, 2014 From my tests there is no advantage in using the ETC mode unless you're not planning to do any post work. I did not really get the buzz around ETC anyway. The only reason is avoiding work in post as you are stating. Quote Link to comment Share on other sites More sharing options...
Guest 560a4aedcb80685284629074497fdc75 Posted December 2, 2014 Share Posted December 2, 2014 Quote Link to comment Share on other sites More sharing options...
johnnymossville Posted December 2, 2014 Share Posted December 2, 2014 ETC mode was great when we didn't have 4k. it allowed us to have two focal lengths with one lens. Of course, it needed quite a bit of light to keep noise down, but it was very useful on the GH2. It's not quite as useful on the GH4 since we currently mostly shoot 4k and edit in 1080P. Quote Link to comment Share on other sites More sharing options...
Vesku Posted December 2, 2014 Author Share Posted December 2, 2014 I made better samples. http://***URL removed***/forums/post/54849358 1. 4k center crop 2. 4k 2x dig zoom downsampled to fullhd 3. ETC fullhd 4. best JPG center crop 1920x1080 5. RAW (ACR) center crop 1920x1080 I noticed that the sensor debayering ruins fine color detail even in RAW photo and levels the differences of different modes. GH4 4:2:0 4k video and ETC is very close to best camera JPG in 100% sensor readout. 4:4:4 RAW is sharper but not perfect. If I use 4k/2x dig zoom I get a little sharper result that cropping 4k or using ETC. I think that Samsung NX1 with 6.5k sensor debayering and downsampling is maybe far better than GH4 in 4k video. I think that even 100% RAW is worse in GH4. We will see. Quote Link to comment Share on other sites More sharing options...
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