Fix MSVC warnings (C4244, C4267, C4305, C4838)

[MajorMurphy]

Goal

CMakeLists.txt mentioned a TODO task of fixing several MSVC warnings

# Disable specific warnings
# TODO: None of these should be disabled, but for now, for a warning-free msvc build these are
# added. fix the warnings and remove these filters
add_compile_options(/wd4244) # conversion from 'type1' to 'type2', possible loss of data
add_compile_options(/wd4267) # conversion from 'size_t' to 'type' possible loss of data
add_compile_options(/wd4305) # truncation from 'double' to 'float'
add_compile_options(/wd4838) # conversion from 'type1' to 'type2' requires a narrowing conversion
add_compile_options(/wd26812) # Prefer enum class over enum

Solution

Upon removing the suppressors, warnings were not visible until explicitly setting warning level /W3. MSVC defaults to /W1, which is not high enough to display these warning messages. Setting it to /W3 makes it consistent with the -Wall -Wextra for non-MSVC builds

target_compile_options(${UHDR_CORE_LIB_NAME} PRIVATE /W3)

All occurrences of C4244, C4267, C4305, C4838 were resolved.
Edited files:

• gainmapmath.h
• gainmapmath.cpp
• icc.cpp
• jpegdecoderhelper.cpp
• jpegencoderhelper.cpp
• jpegr.cpp
• multipictureformat.cpp

C26812 was not observed, even when building with /analyze, so that warning suppression was also removed.

Further warning messages do occur at W4 level, which could be addressed in a future pull request.

Tested

Visual Studio 2026 :

• Successfully compiled and passed all unit tests
• Tested basic decode/encode functionality
• SDK 10.0.26100.0, targeting Win 10.0.26200

Ubuntu:

• Successfully compiled and passed all unit tests
• Clang 18.1.3