avfilter/smptebars: fix some 75% color values

They where slightly off.
Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/vsrc_testsrc.c

@@ -1073,12 +1073,12 @@ AVFilter ff_vsrc_rgbtestsrc = {
 
 static const uint8_t rainbow[7][4] = {
     { 180, 128, 128, 255 },     /* 75% white */
-    { 161,  44, 141, 255 },     /* 75% yellow */
+    { 162,  44, 142, 255 },     /* 75% yellow */
     { 131, 156,  44, 255 },     /* 75% cyan */
-    { 112,  72,  57, 255 },     /* 75% green */
-    {  83, 183, 198, 255 },     /* 75% magenta */
-    {  65,  99, 212, 255 },     /* 75% red */
-    {  34, 212, 114, 255 },     /* 75% blue */
+    { 112,  72,  58, 255 },     /* 75% green */
+    {  84, 184, 198, 255 },     /* 75% magenta */
+    {  65, 100, 212, 255 },     /* 75% red */
+    {  35, 212, 114, 255 },     /* 75% blue */
 };
 
 static const uint8_t rainbowhd[7][4] = {
@@ -1092,9 +1092,9 @@ static const uint8_t rainbowhd[7][4] = {
 };
 
 static const uint8_t wobnair[7][4] = {
-    {  34, 212, 114, 255 },     /* 75% blue */
+    {  35, 212, 114, 255 },     /* 75% blue */
     {  19, 128, 128, 255 },     /* 7.5% intensity black */
-    {  83, 183, 198, 255 },     /* 75% magenta */
+    {  84, 184, 198, 255 },     /* 75% magenta */
     {  19, 128, 128, 255 },     /* 7.5% intensity black */
     { 131, 156,  44, 255 },     /* 75% cyan */
     {  19, 128, 128, 255 },     /* 7.5% intensity black */