Jump to content
You must now use your email address to sign in [click for more info] ×

James Ritson

Staff
  • Posts

    854
  • Joined

  • Last visited

Posts posted by James Ritson

  1. 8 hours ago, kuhl said:

    Hello.

    I am a fan of Affinity tools.
    I am shooting with an a7III.

    The pixel count of an a7III is 6000*4000.
    But when I load the RAW in Photo2, it changes to 6024*4024.
    (Not 3:2 aspect ratio.)

    I am stumped because of the loss of resolution.
    Is there any way to improve it?

    Thanks.

    Hi Kulh, as DM1 mentioned above this is not a loss of resolution—you will find that most RAW files contain a handful of pixels around the edges, but these are cropped away as per the mandated resolution in the metadata. Photo ignores this, however, and always processes the full width and height of the image, which is why you end up with a marginally higher resolution than you would expect. The aspect ratio is still 3:2.

    A good example of this is the Olympus cameras: e.g. the E-M1 mk3's actual RAW resolution is 5240x3912, but the metadata instructs software to crop it to 5184x3888. It doesn't sound like much, but the extra resolution is actually quite welcome when dealing with wider angle lenses. If Photo applies automatic lens corrections, you can actually go into the Lens tab and bring Scale down—you'll often find there is pixel data being pushed outside of the crop bounds that you can bring back, and this is made partially possible by Photo not cropping those edge pixels.

    Hope that helps!

  2. Hope everyone had a lovely Christmas!

    I wanted to sneak in another video before the new year, so here you go:

    HDR/EDR technology has actually been present in Affinity Photo for a few years now (since around 1.7 I believe), but with V2 introducing JPEG-XL export I thought it was about time to do a proper video on high dynamic range editing. This video was shot in HDR and mastered to 1600 nits of peak brightness, so if you have a display capable of that brightness (for example, the M1 Pro/Max MacBook displays), you're in for a visual treat! For those viewing on SDR displays, the content will be tone mapped and will of course lose a bit of its impact...

  3. 2 hours ago, Claude_ch said:

    Hi,

    the Tone Mapping was by default.

    When I open the .exr (RGB/32) it's all white. Then I add a live exposure adjustment for bring back the picture. And when I convert in RGB/16 or RGB/8 I lose all data and the picture is black. Maybe the value from DAZ for .exr are out of the ordinary and when Affinity Photo try to converts it's going wrong. I send the .exr file on dropbox ;)

    And for your Live Procedural Texture, works better as with the exposure adjustment, the color are less saturated. I need juste a crazy number for the compression Scale... 13'000 for example. It's very close with the 8bits png version what DAZ save a the same time.

    The picture going black will be because:

    • Your original EXR document contains pixel values greater than 1
    • Unless you merge down the Exposure adjustment before converting to RGB/16 or RGB/8, you will then lose (clip) those >1 values
    • This is because the Exposure adjustment is then being applied to the bounded range of pixel values, so it is taking the maximum value (255 in 8-bit, 65535 in 16-bit) and reducing it down to 0.

    The solution is either to merge the Exposure adjustment before converting, or to simply stay in RGB/32 and use a tone mapping method after the Exposure adjustment (e.g. procedural texture, or Levels adjustment followed by other adjustments).

    Hope that helps!

  4. Hi @Gary.JONES, the procedure for selecting the best light frames is based on the quality of the 40 best stars found in each sub, where a good star is bright relative to the noise level, round, sufficient size (but not too big) with peaks in the middle. The help documentation may need updating as I don't believe that information is completely accurate...

  5. 1 hour ago, Claude_ch said:

    Hi,

    So when I render with DAZ Studio Pro and save that file as an exr file and then open it in Affinity Photo, it's all white. I need to add an exposure adjustment to see the image. The image is an RGB/32 bit format, now when I want to convert this image to RGB/16 or RGB/8, the image becomes all black.

    The turn around solution is, I need rasterise the image with the exposure adjustment included and then convert in RGB/16 or RGB/8 and that works.

     

    PS I added the file, if you need the exr file,tell me ;)

    Victoria.afphoto 29.49 MB · 2 downloads

    Hey Claude,

    This could actually be by design—I haven't used DAZ, but could relate using blender. There's more of a focus on physically correct lighting nowadays, and many of blender's environment/sky lighting plugins (such as True Sky, Physical Starlight and Atmosphere etc) will use incredibly bright values that then require the Exposure to be reduced significantly, usually by 3 to 6 stops.

    This is fine when you are writing out gamma-corrected bitmap files such as TIFF and JPEG, but when saving to EXR this tone mapping isn't applied to the pixel values—instead, you're getting the unmodified pixel values in linear gamma. This is by design, as software shouldn't really be writing any kind of gamma encoded values to EXR.

    If you colour pick one of the white values when you first import your EXR, I imagine the value would be greater than 1. What are your tone mapping/view settings in DAZ? It may be you're using some kind of lighting that requires the Exposure value to be reduced, and you would then have to match that in Affinity Photo with an Exposure adjustment layer.

    Your solution is sound in practice, but I would be wary of clipped or 'harsh' highlight details because you may also need to apply some kind of tone mapping to give highlights a roll-off effect. This should be done in 32-bit before merging/flattening and converting to 16-bit or 8-bit, which are bounded gamma corrected formats.

    This video might be of help: 

     

     

    Hope the above helps!

  6. I think it helps to simplify things as much as possible. In this case, clipped tones are essentially colour values that do not fit within the available output colour space (such as the default sRGB profile), usually because they are too intense.

    There are a couple of solutions to this: you could change the output profile to something wider such as ROMM RGB (notice how the histogram shifts when doing so), or you can use a combination of exposure, brightness, black point, saturation/vibrance, shadows and highlights to “compress” or make the tones fit within the available range of colour values.

    The first solution of using a wider colour profile does introduce potential pitfalls with colour management (such as the infamous colour shift when viewing images with a wider colour space in an unmanaged view). Most web browsers are colour managed nowadays, but it’s still often recommended to convert to sRGB during export to ensure maximum compatibility.

    The second solution usually means you end up compressing the tones more, typically when using the highlights slider. This is fine, but just keep an eye on the actual image rather than the histogram—this leads me onto the next point…

    Outside of some edge-case workflows (such as high end VFX), the whole concept of clipped tones lends itself to more of a creative decision—you might have some intense red and blue colour values, for example, that cannot be represented in sRGB, and so will simply be clipped to the maximum channel value. This isn’t necessarily the end of the world! You can most likely craft a perfectly good image within the constraints of sRGB as it does tend to represent the majority of colour intensity values seen in everyday life with reflected light.

    I wouldn’t spend too much time worrying about it, to be honest. Does the image look good on screen in sRGB? If not, and you’re happy to involve wider colour spaces in your workflow, try a wider profile such as ROMM RGB. But don’t get bogged down with it too much! The time worrying about whether some clipped tones are compromising image quality is arguably better spent learning some useful post-processing techniques for the kind of imagery most likely to have intense colours (e.g. low light, urban scenes with artificial lighting). HSL, Selective Colour, brush work on pixel layers with blend modes are just a few ideas, but there are many more.

    Hope the above is helpful!

×
×
  • Create New...

Important Information

Terms of Use | Privacy Policy | Guidelines | We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.