Ktor not serving static images properly

Question

I have a ktor server, and I'm trying to serve some static assets that are stored in resources folder assets.

static("/assets") {
    resources("assets")
}

For .css files it works when I fetch them with something like http://0.0.0.0:7200/assets/css/main.css, but when I try to fetch images with http://localhost:7200/assets/img/flags/uk.png, it returns a broken image, although it exists.

I've tried different image formats and paths. Also tried different ways of serving the resources, but none worked.

Edit (Beginning of image downloaded from browser):

Edit (Beginning of original file, why are they slightly different?):

Answer 1

Finally I found the issue. It had nothing to do with Ktor, but with Gradle. Let me explain. I have this configuration in my build.gradle.kts file:

tasks.processResources {
    from(sourceSets["main"].resources.srcDirs)
    into("$buildDir/resources/main")
    duplicatesStrategy = DuplicatesStrategy.INCLUDE

        filter(
            ReplaceTokens::class, "tokens" to mapOf(
                "BUILD_VERSION" to version,
                "BUILD_DATE" to DateTimeFormatter.ISO_DATE_TIME.format(ZonedDateTime.now()),
                "BUILD_MACHINE" to InetAddress.getLocalHost().hostName
            )
        )
}

And for some reason, it was messing around the images. Solution, apply the processing only to the files I want, in this case, only application.conf. So I now have it like this, and it doesn't corrupt image files from resources:

tasks.processResources {
    from(sourceSets["main"].resources.srcDirs)
    into("$buildDir/resources/main")
    duplicatesStrategy = DuplicatesStrategy.INCLUDE

    filesMatching("application.conf") {
        filter(
            ReplaceTokens::class, "tokens" to mapOf(
                "BUILD_VERSION" to version,
                "BUILD_DATE" to DateTimeFormatter.ISO_DATE_TIME.format(ZonedDateTime.now()),
                "BUILD_MACHINE" to InetAddress.getLocalHost().hostName
            )
        )
    }
}

Thank you all for your willingness to help.