From f0b2f2937161436f1a90b01d9c524d7a7c3e6385 Mon Sep 17 00:00:00 2001 From: Yannis Guyon Date: Mon, 21 Oct 2024 14:31:10 +0000 Subject: [PATCH] Consistently use dfn noexport for derived items (#261) To make sure the first sentence of each derived image item section is rendered in a similar way. --- index.bs | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/index.bs b/index.bs index b359bbb..650d1ac 100755 --- a/index.bs +++ b/index.bs @@ -396,17 +396,17 @@ A grid derived image item ('[=grid=]') as defin

Tone Map Derived Image Item

-A tone map derived image item ('[=tmap=]') as defined in [[!HEIF]] may be used in an [=AVIF file=]. When present, the base image item and the '[=tmap=]' image item should be grouped together by an '[=altr=]' (see [[#altr-group]]) entity group as recommended in [[!HEIF]]. +A tone map derived image item ('[=tmap=]') as defined in [[!HEIF]] may be used in an [=AVIF file=]. When present, the base image item and the '[=tmap=]' image item should be grouped together by an '[=altr=]' (see [[#altr-group]]) entity group as recommended in [[!HEIF]].

Sample Transform Derived Image Item

-With a [=Sample Transform Derived Image Item=], pixels at the same position in multiple input image items can be combined into a single output pixel using basic mathematical operations. This can for example be used to work around codec limitations or for storing alterations to an image as non-destructive residuals. With a [=Sample Transform Derived Image Item=] it is possible for [=/AVIF=] to support 16 or more bits of precision per sample, while still offering backward compatibility through a regular 8 to 12-bit [=AV1 Image Item=] containing the most significant bits of each sample. +With a Sample Transform Derived Image Item, pixels at the same position in multiple input image items can be combined into a single output pixel using basic mathematical operations. This can for example be used to work around codec limitations or for storing alterations to an image as non-destructive residuals. With a [=Sample Transform Derived Image Item=] it is possible for [=/AVIF=] to support 16 or more bits of precision per sample, while still offering backward compatibility through a regular 8 to 12-bit [=AV1 Image Item=] containing the most significant bits of each sample. In these sections, a "sample" refers to the value of a pixel for a given channel.
Definition
-When a [=derived image item=] is of type sato, it is called a Sample Transform Derived Image Item, and its reconstructed image is formed from a set of input image items, [=sato/constants=] and [=sato/operators=]. +When a [=derived image item=] is of type sato, it is called a [=Sample Transform Derived Image Item=], and its reconstructed image is formed from a set of input image items, [=sato/constants=] and [=sato/operators=]. The input images are specified in the [=SingleItemTypeReferenceBox=] or [=SingleItemTypeReferenceBoxLarge=] entries of type '[=dimg=]' for this [=Sample Transform Derived Image Item=] within the [=ItemReferenceBox=]. The input images are in the same order as specified in these entries. In the [=SingleItemTypeReferenceBox=] or [=SingleItemTypeReferenceBoxLarge=] of type '[=dimg=]', the value of the [=from_item_ID=] field identifies the [=Sample Transform Derived Image Item=], and the values of the [=to_item_ID=] field identify the input images. There are [=reference_count=] input image items as specified by the [=ItemReferenceBox=].