here is your npm api
var gulp = require('gulp');
var imagemin = require('gulp-tinypng');
gulp.task('tinypng', function () {
gulp.src('src/image.png')
.pipe(tingpng('API_KEY'))
.pipe(gulp.dest('dist'));
});
I change it to this, and it works.
var gulp = require('gulp');
var imagemin = require('gulp-tinypng');
gulp.task('tinypng', function () {
gulp.src('./images/tinypng/*.{jpg,png,gif,jpeg}')
.pipe(tinypng('API_key'))
//api_key may need to buy?
.pipe(gulp.dest('./images'));
});