def find_edge_pair(data, y, roi_width, edgeThreshold=450):
'''
find_edge_pair finds the edge of a slit pair in a flat
data[2048x2048]: a well illuminated flat field [DN]
y: guess of slit edge position [pix]
Keywords:
edgeThreshold: the pixel value below which we should ignore using
to calculate edges.
Moves along the edge of a slit image
- At each location along the slit edge, determines
the position of the demarcations between two slits
Outputs:
xposs []: Array of x positions along the slit edge [pix]
yposs []: The fitted y positions of the "top" edge of the slit [pix]
widths []: The fitted delta from the top edge of the bottom [pix]
scatters []: The amount of light between slits
The procedure is as follows
1: starting from a guess spatial position (parameter y), march
along the spectral direction in some chunk of pixels
2: At each spectral location, construct a cross cut across the
spatial direction; select_roi is used for this.
3: Fit a two-sided error function Fit.residual_disjoint_pair
on the vertical cross cut derived in step 2.
4: If the fit fails, store it in the missing list
- else if the top fit is good, store the top values in top vector
- else if the bottom fit is good, store the bottom values in bottom
vector.
5: In the vertical cross-cut, there is a minimum value. This minimum
value is stored as a measure of scattered light.
Another procedure is used to fit polynomials to these fitted values.
'''
def select_roi(data, roi_width):
v = data[y - roi_width:y + roi_width, xp - 2:xp + 2]
v = np.median(v, axis=1) # Axis = 1 is spatial direction
return v
xposs_top = []
yposs_top = []
xposs_top_missing = []
xposs_bot = []
yposs_bot = []
xposs_bot_missing = []
yposs_bot_scatters = []
#1
rng = np.linspace(10, 2040, 50).astype(np.int)
for i in rng:
xp = i
#2
v = select_roi(data, roi_width)
xs = np.arange(len(v))
# Modified from 450 as the hard coded threshold to one that
# can be controlled by a keyword
if (np.median(v) < edgeThreshold):
xposs_top_missing.append(xp)
xposs_bot_missing.append(xp)
continue
#3
ff = Fit.do_fit(v, residual_fun=Fit.residual_disjoint_pair)
fit_ok = 0 < ff[4] < 4
if fit_ok:
(sigma, offset, mult1, mult2, add, width) = ff[0]
xposs_top.append(xp)
yposs_top.append(y - roi_width + offset + width)
xposs_bot.append(xp)
yposs_bot.append(y - roi_width + offset)
between = offset + width / 2
if 0 < between < len(v) - 1:
start = np.max([0, between - 2])
stop = np.min([len(v), between + 2])
yposs_bot_scatters.append(np.min(v[start:stop])) # 5
if False:
pl.figure(2)
pl.clf()
tmppix = np.arange(y - roi_width, y + roi_width)
tmpx = np.arange(len(v))
pl.axvline(y - roi_width + offset + width, color='red')
pl.axvline(y - roi_width + offset, color='red')
pl.scatter(tmppix, v)
pl.plot(tmppix, Fit.fit_disjoint_pair(ff[0], tmpx))
pl.axhline(yposs_bot_scatters[-1])
pl.draw()
else:
yposs_bot_scatters.append(np.nan)
else:
xposs_bot_missing.append(xp)
xposs_top_missing.append(xp)
info("Skipping wavelength pixel): %i" % (xp))
return map(np.array, (xposs_bot, xposs_bot_missing, yposs_bot, xposs_top,
xposs_top_missing, yposs_top, yposs_bot_scatters))
def find_edge_pair(data, y, roi_width, edgeThreshold=450):
'''
find_edge_pair finds the edge of a slit pair in a flat
data[2048x2048]: a well illuminated flat field [DN]
y: guess of slit edge position [pix]
Keywords:
edgeThreshold: the pixel value below which we should ignore using
to calculate edges.
Moves along the edge of a slit image
- At each location along the slit edge, determines
the position of the demarcations between two slits
Outputs:
xposs []: Array of x positions along the slit edge [pix]
yposs []: The fitted y positions of the "top" edge of the slit [pix]
widths []: The fitted delta from the top edge of the bottom [pix]
scatters []: The amount of light between slits
The procedure is as follows
1: starting from a guess spatial position (parameter y), march
along the spectral direction in some chunk of pixels
2: At each spectral location, construct a cross cut across the
spatial direction; select_roi is used for this.
3: Fit a two-sided error function Fit.residual_disjoint_pair
on the vertical cross cut derived in step 2.
4: If the fit fails, store it in the missing list
- else if the top fit is good, store the top values in top vector
- else if the bottom fit is good, store the bottom values in bottom
vector.
5: In the vertical cross-cut, there is a minimum value. This minimum
value is stored as a measure of scattered light.
Another procedure is used to fit polynomials to these fitted values.
'''
def select_roi(data, roi_width):
v = data[y-roi_width:y+roi_width, xp-2:xp+2]
v = np.median(v, axis=1) # Axis = 1 is spatial direction
return v
xposs_top = []
yposs_top = []
xposs_top_missing = []
xposs_bot = []
yposs_bot = []
xposs_bot_missing = []
yposs_bot_scatters = []
#1
rng = np.linspace(10, 2040, 50).astype(np.int)
for i in rng:
xp = i
#2
v = select_roi(data, roi_width)
xs = np.arange(len(v))
# Modified from 450 as the hard coded threshold to one that
# can be controlled by a keyword
if (np.median(v) < edgeThreshold):
xposs_top_missing.append(xp)
xposs_bot_missing.append(xp)
continue
#3
ff = Fit.do_fit(v, residual_fun=Fit.residual_disjoint_pair)
fit_ok = 0 < ff[4] < 4
if fit_ok:
(sigma, offset, mult1, mult2, add, width) = ff[0]
xposs_top.append(xp)
yposs_top.append(y - roi_width + offset + width)
xposs_bot.append(xp)
yposs_bot.append(y - roi_width + offset)
between = offset + width/2
if 0 < between < len(v)-1:
start = np.max([0, between-2])
stop = np.min([len(v),between+2])
yposs_bot_scatters.append(np.min(v[start:stop])) # 5
if False:
pl.figure(2)
pl.clf()
tmppix = np.arange(y-roi_width, y+roi_width)
tmpx = np.arange(len(v))
pl.axvline(y - roi_width + offset + width, color='red')
pl.axvline(y - roi_width + offset, color='red')
pl.scatter(tmppix, v)
pl.plot(tmppix, Fit.fit_disjoint_pair(ff[0], tmpx))
pl.axhline(yposs_bot_scatters[-1])
pl.draw()
else:
yposs_bot_scatters.append(np.nan)
else:
xposs_bot_missing.append(xp)
xposs_top_missing.append(xp)
info("Skipping wavelength pixel): %i" % (xp))
return map(np.array, (xposs_bot, xposs_bot_missing, yposs_bot, xposs_top,
xposs_top_missing, yposs_top, yposs_bot_scatters))
