diff --git a/src/enc/syntax.c b/src/enc/syntax.c
index 40efa63b..a788f3c3 100644
--- a/src/enc/syntax.c
+++ b/src/enc/syntax.c
@@ -86,24 +86,13 @@ static void PutSegmentHeader(VP8BitWriter* const bw,
     int s;
     VP8PutBitUniform(bw, hdr->update_map_);
     if (VP8PutBitUniform(bw, update_data)) {
-      const int base_quant = enc->base_quant_;
-      const int base_strength = enc->filter_hdr_.level_;
-      VP8PutBitUniform(bw, hdr->absolute_delta_);
+      // we always use absolute values, not relative ones
+      VP8PutBitUniform(bw, 1);   // (segment_feature_mode = 1. Paragraph 9.3.)
       for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
-        if (hdr->absolute_delta_) {
-          VP8PutSignedValue(bw, enc->dqm_[s].quant_, 7);
-        } else {
-          const int delta = enc->dqm_[s].quant_ - base_quant;
-          VP8PutSignedValue(bw, delta, 7);
-        }
+        VP8PutSignedValue(bw, enc->dqm_[s].quant_, 7);
       }
       for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
-        if (hdr->absolute_delta_) {
-          VP8PutSignedValue(bw, enc->dqm_[s].fstrength_, 6);
-        } else {
-          const int delta = enc->dqm_[s].fstrength_ - base_strength;
-          VP8PutSignedValue(bw, delta, 6);
-        }
+        VP8PutSignedValue(bw, enc->dqm_[s].fstrength_, 6);
       }
     }
     if (hdr->update_map_) {
diff --git a/src/enc/vp8enci.h b/src/enc/vp8enci.h
index 4593d564..25f50eed 100644
--- a/src/enc/vp8enci.h
+++ b/src/enc/vp8enci.h
@@ -159,9 +159,6 @@ typedef struct {
   int num_segments_;      // Actual number of segments. 1 segment only = unused.
   int update_map_;        // whether to update the segment map or not.
                           // must be 0 if there's only 1 segment.
-  int absolute_delta_;    // if true, segments' filter strength and quantizers
-                          // are not transmitted relatively to
-                          // VP8FilterHeader::level_ and base_quant_
   int size_;              // bit-cost for transmitting the segment map
 } VP8SegmentHeader;
 
diff --git a/src/enc/webpenc.c b/src/enc/webpenc.c
index ca2dfd13..5ca445ef 100644
--- a/src/enc/webpenc.c
+++ b/src/enc/webpenc.c
@@ -55,7 +55,6 @@ static void ResetSegmentHeader(VP8Encoder* const enc) {
   VP8SegmentHeader* const hdr = &enc->segment_hdr_;
   hdr->num_segments_ = enc->config_->segments;
   hdr->update_map_  = (hdr->num_segments_ > 1);
-  hdr->absolute_delta_ = 1;
   hdr->size_ = 0;
 }
 
@@ -285,7 +284,9 @@ int WebPEncode(const WebPConfig* const config, WebPPicture* const pic) {
     return 0;   // bad params
   if (!WebPValidateConfig(config))
     return 0;   // invalid config.
-  if (pic->width <= 0 || pic->height <= 0 || pic->y == NULL)
+  if (pic->width <= 0 || pic->height <= 0)
+    return 0;   // invalid parameters
+  if (pic->y == NULL || pic->u == NULL || pic->v == NULL)
     return 0;   // invalid parameters
   if (pic->width >= MAX_DIMENSION || pic->height >= MAX_DIMENSION)
     return 0;   // image is too big