diff --git a/doc/filters.texi b/doc/filters.texi
index 867607d870..8a78e2129b 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -11302,6 +11302,21 @@ kerndeint=map=1
 @end example
 @end itemize
 
+@section lagfun
+
+Slowly update darker pixels.
+
+This filter makes short flashes of light appear longer.
+This filter accepts the following options:
+
+@table @option
+@item decay
+Set factor for decaying. Default is .95. Allowed range is from 0 to 1.
+
+@item planes
+Set which planes to filter. Default is all. Allowed range is from 0 to 15.
+@end table
+
 @section lenscorrection
 
 Correct radial lens distortion
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index fef6ec5c55..c215a3ad20 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -266,6 +266,7 @@ OBJS-$(CONFIG_INFLATE_FILTER)                += vf_neighbor.o
 OBJS-$(CONFIG_INTERLACE_FILTER)              += vf_tinterlace.o
 OBJS-$(CONFIG_INTERLEAVE_FILTER)             += f_interleave.o
 OBJS-$(CONFIG_KERNDEINT_FILTER)              += vf_kerndeint.o
+OBJS-$(CONFIG_LAGFUN_FILTER)                 += vf_lagfun.o
 OBJS-$(CONFIG_LENSCORRECTION_FILTER)         += vf_lenscorrection.o
 OBJS-$(CONFIG_LENSFUN_FILTER)                += vf_lensfun.o
 OBJS-$(CONFIG_LIBVMAF_FILTER)                += vf_libvmaf.o framesync.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index c51ae0f3c7..ddac15aa6e 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -252,6 +252,7 @@ extern AVFilter ff_vf_inflate;
 extern AVFilter ff_vf_interlace;
 extern AVFilter ff_vf_interleave;
 extern AVFilter ff_vf_kerndeint;
+extern AVFilter ff_vf_lagfun;
 extern AVFilter ff_vf_lenscorrection;
 extern AVFilter ff_vf_lensfun;
 extern AVFilter ff_vf_libvmaf;
diff --git a/libavfilter/vf_lagfun.c b/libavfilter/vf_lagfun.c
new file mode 100644
index 0000000000..373b41077a
--- /dev/null
+++ b/libavfilter/vf_lagfun.c
@@ -0,0 +1,252 @@
+/*
+ * Copyright (c) 2018 Paul B Mahol
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/imgutils.h"
+#include "libavutil/intreadwrite.h"
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+typedef struct LagfunContext {
+    const AVClass *class;
+    const AVPixFmtDescriptor *desc;
+    float decay;
+    int planes;
+
+    int depth;
+    int nb_planes;
+    int linesize[4];
+    int height[4];
+
+    AVFrame *old;
+
+    int (*lagfun)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
+} LagfunContext;
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum AVPixelFormat pixel_fmts[] = {
+        AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY9,
+        AV_PIX_FMT_GRAY10, AV_PIX_FMT_GRAY12, AV_PIX_FMT_GRAY14,
+        AV_PIX_FMT_GRAY16,
+        AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
+        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
+        AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
+        AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P,
+        AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ444P,
+        AV_PIX_FMT_YUVJ411P,
+        AV_PIX_FMT_YUV420P9, AV_PIX_FMT_YUV422P9, AV_PIX_FMT_YUV444P9,
+        AV_PIX_FMT_YUV420P10, AV_PIX_FMT_YUV422P10, AV_PIX_FMT_YUV444P10,
+        AV_PIX_FMT_YUV440P10,
+        AV_PIX_FMT_YUV444P12, AV_PIX_FMT_YUV422P12, AV_PIX_FMT_YUV420P12,
+        AV_PIX_FMT_YUV440P12,
+        AV_PIX_FMT_YUV444P14, AV_PIX_FMT_YUV422P14, AV_PIX_FMT_YUV420P14,
+        AV_PIX_FMT_YUV420P16, AV_PIX_FMT_YUV422P16, AV_PIX_FMT_YUV444P16,
+        AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRP9, AV_PIX_FMT_GBRP10,
+        AV_PIX_FMT_GBRP12, AV_PIX_FMT_GBRP14, AV_PIX_FMT_GBRP16,
+        AV_PIX_FMT_NONE
+    };
+    AVFilterFormats *formats = ff_make_format_list(pixel_fmts);
+    if (!formats)
+        return AVERROR(ENOMEM);
+    return ff_set_common_formats(ctx, formats);
+}
+
+typedef struct ThreadData {
+    AVFrame *in, *out, *old;
+} ThreadData;
+
+static int lagfun_frame8(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+    LagfunContext *s = ctx->priv;
+    const float decay = s->decay;
+    ThreadData *td = arg;
+    AVFrame *in = td->in;
+    AVFrame *out = td->out;
+    AVFrame *old = td->old;
+
+    for (int p = 0; p < s->nb_planes; p++) {
+        const int slice_start = (s->height[p] * jobnr) / nb_jobs;
+        const int slice_end = (s->height[p] * (jobnr+1)) / nb_jobs;
+        const uint8_t *src = in->data[p] + slice_start * in->linesize[p];
+        uint8_t *osrc = old->data[p] + slice_start * old->linesize[p];
+        uint8_t *dst = out->data[p] + slice_start * out->linesize[p];
+
+        if (!((1 << p) & s->planes)) {
+            av_image_copy_plane(dst, out->linesize[p],
+                                src, in->linesize[p],
+                                s->linesize[p], slice_end - slice_start);
+            continue;
+        }
+
+        for (int y = slice_start; y < slice_end; y++) {
+            for (int x = 0; x < s->linesize[p]; x++)
+                dst[x] = FFMAX(src[x], osrc[x] * decay);
+
+            src += in->linesize[p];
+            osrc += old->linesize[p];
+            dst += out->linesize[p];
+        }
+    }
+
+    return 0;
+}
+
+static int lagfun_frame16(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
+{
+    LagfunContext *s = ctx->priv;
+    const float decay = s->decay;
+    ThreadData *td = arg;
+    AVFrame *in = td->in;
+    AVFrame *out = td->out;
+    AVFrame *old = td->old;
+
+    for (int p = 0; p < s->nb_planes; p++) {
+        const int slice_start = (s->height[p] * jobnr) / nb_jobs;
+        const int slice_end = (s->height[p] * (jobnr+1)) / nb_jobs;
+        const uint16_t *src = (uint16_t *)in->data[p] + slice_start * in->linesize[p] / 2;
+        uint16_t *osrc = (uint16_t *)old->data[p] + slice_start * old->linesize[p] / 2;
+        uint16_t *dst = (uint16_t *)out->data[p] + slice_start * out->linesize[p] / 2;
+
+        if (!((1 << p) & s->planes)) {
+            av_image_copy_plane((uint8_t *)dst, out->linesize[p],
+                                (uint8_t *)src, in->linesize[p],
+                                s->linesize[p], slice_end - slice_start);
+            continue;
+        }
+
+        for (int y = slice_start; y < slice_end; y++) {
+            for (int x = 0; x < s->linesize[p]; x++)
+                dst[x] = FFMAX(src[x], osrc[x] * decay);
+
+            src += in->linesize[p] / 2;
+            osrc += old->linesize[p] / 2;
+            dst += out->linesize[p] / 2;
+        }
+    }
+
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    LagfunContext *s = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+    int ret;
+
+    s->desc = av_pix_fmt_desc_get(outlink->format);
+    if (!s->desc)
+        return AVERROR_BUG;
+    s->nb_planes = av_pix_fmt_count_planes(outlink->format);
+    s->depth = s->desc->comp[0].depth;
+    s->lagfun = s->depth <= 8 ? lagfun_frame8 : lagfun_frame16;
+
+    if ((ret = av_image_fill_linesizes(s->linesize, inlink->format, inlink->w)) < 0)
+        return ret;
+
+    s->height[1] = s->height[2] = AV_CEIL_RSHIFT(inlink->h, s->desc->log2_chroma_h);
+    s->height[0] = s->height[3] = inlink->h;
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    LagfunContext *s = ctx->priv;
+    ThreadData td;
+    AVFrame *out;
+
+    if (!s->old) {
+        s->old = av_frame_clone(in);
+        return ff_filter_frame(outlink, in);
+    }
+
+    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
+    if (!out) {
+        av_frame_free(&in);
+        return AVERROR(ENOMEM);
+    }
+    out->pts = in->pts;
+
+    td.out = out;
+    td.in = in;
+    td.old = s->old;
+    ctx->internal->execute(ctx, s->lagfun, &td, NULL, FFMIN(s->height[1], ff_filter_get_nb_threads(ctx)));
+
+    av_frame_free(&s->old);
+    av_frame_free(&in);
+    s->old = av_frame_clone(out);
+    return ff_filter_frame(outlink, out);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    LagfunContext *s = ctx->priv;
+
+    av_frame_free(&s->old);
+}
+
+#define OFFSET(x) offsetof(LagfunContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption lagfun_options[] = {
+    { "decay",  "set decay",                 OFFSET(decay),  AV_OPT_TYPE_FLOAT, {.dbl=.95},  0,  1,  FLAGS },
+    { "planes", "set what planes to filter", OFFSET(planes), AV_OPT_TYPE_FLAGS, {.i64=15},   0, 15,  FLAGS },
+    { NULL },
+};
+
+static const AVFilterPad inputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .filter_frame  = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = config_output,
+    },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(lagfun);
+
+AVFilter ff_vf_lagfun = {
+    .name          = "lagfun",
+    .description   = NULL_IF_CONFIG_SMALL("Slowly update pixels."),
+    .priv_size     = sizeof(LagfunContext),
+    .priv_class    = &lagfun_class,
+    .query_formats = query_formats,
+    .uninit        = uninit,
+    .outputs       = outputs,
+    .inputs        = inputs,
+    .flags         = AVFILTER_FLAG_SLICE_THREADS,
+};
